1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc_implementation/g1/bufferingOopClosure.hpp" 31 #include "gc_implementation/g1/concurrentG1Refine.hpp" 32 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 34 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 35 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 36 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 37 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 38 #include "gc_implementation/g1/g1EvacFailure.hpp" 39 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 40 #include "gc_implementation/g1/g1Log.hpp" 41 #include "gc_implementation/g1/g1MarkSweep.hpp" 42 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 43 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 44 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 45 #include "gc_implementation/g1/g1RemSet.inline.hpp" 46 #include "gc_implementation/g1/g1RootProcessor.hpp" 47 #include "gc_implementation/g1/g1StringDedup.hpp" 48 #include "gc_implementation/g1/g1YCTypes.hpp" 49 #include "gc_implementation/g1/heapRegion.inline.hpp" 50 #include "gc_implementation/g1/heapRegionRemSet.hpp" 51 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 52 #include "gc_implementation/g1/vm_operations_g1.hpp" 53 #include "gc_implementation/shared/gcHeapSummary.hpp" 54 #include "gc_implementation/shared/gcTimer.hpp" 55 #include "gc_implementation/shared/gcTrace.hpp" 56 #include "gc_implementation/shared/gcTraceTime.hpp" 57 #include "gc_implementation/shared/isGCActiveMark.hpp" 58 #include "memory/allocation.hpp" 59 #include "memory/gcLocker.inline.hpp" 60 #include "memory/generationSpec.hpp" 61 #include "memory/iterator.hpp" 62 #include "memory/referenceProcessor.hpp" 63 #include "oops/oop.inline.hpp" 64 #include "runtime/atomic.inline.hpp" 65 #include "runtime/orderAccess.inline.hpp" 66 #include "runtime/vmThread.hpp" 67 #include "utilities/globalDefinitions.hpp" 68 #include "utilities/stack.inline.hpp" 69 #include "utilities/taskqueue.inline.hpp" 70 71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 72 73 // turn it on so that the contents of the young list (scan-only / 74 // to-be-collected) are printed at "strategic" points before / during 75 // / after the collection --- this is useful for debugging 76 #define YOUNG_LIST_VERBOSE 0 77 // CURRENT STATUS 78 // This file is under construction. Search for "FIXME". 79 80 // INVARIANTS/NOTES 81 // 82 // All allocation activity covered by the G1CollectedHeap interface is 83 // serialized by acquiring the HeapLock. This happens in mem_allocate 84 // and allocate_new_tlab, which are the "entry" points to the 85 // allocation code from the rest of the JVM. (Note that this does not 86 // apply to TLAB allocation, which is not part of this interface: it 87 // is done by clients of this interface.) 88 89 // Local to this file. 90 91 class RefineCardTableEntryClosure: public CardTableEntryClosure { 92 bool _concurrent; 93 public: 94 RefineCardTableEntryClosure() : _concurrent(true) { } 95 96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 98 // This path is executed by the concurrent refine or mutator threads, 99 // concurrently, and so we do not care if card_ptr contains references 100 // that point into the collection set. 101 assert(!oops_into_cset, "should be"); 102 103 if (_concurrent && SuspendibleThreadSet::should_yield()) { 104 // Caller will actually yield. 105 return false; 106 } 107 // Otherwise, we finished successfully; return true. 108 return true; 109 } 110 111 void set_concurrent(bool b) { _concurrent = b; } 112 }; 113 114 115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 116 private: 117 size_t _num_processed; 118 119 public: 120 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 121 122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 123 *card_ptr = CardTableModRefBS::dirty_card_val(); 124 _num_processed++; 125 return true; 126 } 127 128 size_t num_processed() const { return _num_processed; } 129 }; 130 131 YoungList::YoungList(G1CollectedHeap* g1h) : 132 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 133 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 134 guarantee(check_list_empty(false), "just making sure..."); 135 } 136 137 void YoungList::push_region(HeapRegion *hr) { 138 assert(!hr->is_young(), "should not already be young"); 139 assert(hr->get_next_young_region() == NULL, "cause it should!"); 140 141 hr->set_next_young_region(_head); 142 _head = hr; 143 144 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 145 ++_length; 146 } 147 148 void YoungList::add_survivor_region(HeapRegion* hr) { 149 assert(hr->is_survivor(), "should be flagged as survivor region"); 150 assert(hr->get_next_young_region() == NULL, "cause it should!"); 151 152 hr->set_next_young_region(_survivor_head); 153 if (_survivor_head == NULL) { 154 _survivor_tail = hr; 155 } 156 _survivor_head = hr; 157 ++_survivor_length; 158 } 159 160 void YoungList::empty_list(HeapRegion* list) { 161 while (list != NULL) { 162 HeapRegion* next = list->get_next_young_region(); 163 list->set_next_young_region(NULL); 164 list->uninstall_surv_rate_group(); 165 // This is called before a Full GC and all the non-empty / 166 // non-humongous regions at the end of the Full GC will end up as 167 // old anyway. 168 list->set_old(); 169 list = next; 170 } 171 } 172 173 void YoungList::empty_list() { 174 assert(check_list_well_formed(), "young list should be well formed"); 175 176 empty_list(_head); 177 _head = NULL; 178 _length = 0; 179 180 empty_list(_survivor_head); 181 _survivor_head = NULL; 182 _survivor_tail = NULL; 183 _survivor_length = 0; 184 185 _last_sampled_rs_lengths = 0; 186 187 assert(check_list_empty(false), "just making sure..."); 188 } 189 190 bool YoungList::check_list_well_formed() { 191 bool ret = true; 192 193 uint length = 0; 194 HeapRegion* curr = _head; 195 HeapRegion* last = NULL; 196 while (curr != NULL) { 197 if (!curr->is_young()) { 198 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 199 "incorrectly tagged (y: %d, surv: %d)", 200 p2i(curr->bottom()), p2i(curr->end()), 201 curr->is_young(), curr->is_survivor()); 202 ret = false; 203 } 204 ++length; 205 last = curr; 206 curr = curr->get_next_young_region(); 207 } 208 ret = ret && (length == _length); 209 210 if (!ret) { 211 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 212 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 213 length, _length); 214 } 215 216 return ret; 217 } 218 219 bool YoungList::check_list_empty(bool check_sample) { 220 bool ret = true; 221 222 if (_length != 0) { 223 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 224 _length); 225 ret = false; 226 } 227 if (check_sample && _last_sampled_rs_lengths != 0) { 228 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 229 ret = false; 230 } 231 if (_head != NULL) { 232 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 233 ret = false; 234 } 235 if (!ret) { 236 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 237 } 238 239 return ret; 240 } 241 242 void 243 YoungList::rs_length_sampling_init() { 244 _sampled_rs_lengths = 0; 245 _curr = _head; 246 } 247 248 bool 249 YoungList::rs_length_sampling_more() { 250 return _curr != NULL; 251 } 252 253 void 254 YoungList::rs_length_sampling_next() { 255 assert( _curr != NULL, "invariant" ); 256 size_t rs_length = _curr->rem_set()->occupied(); 257 258 _sampled_rs_lengths += rs_length; 259 260 // The current region may not yet have been added to the 261 // incremental collection set (it gets added when it is 262 // retired as the current allocation region). 263 if (_curr->in_collection_set()) { 264 // Update the collection set policy information for this region 265 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 266 } 267 268 _curr = _curr->get_next_young_region(); 269 if (_curr == NULL) { 270 _last_sampled_rs_lengths = _sampled_rs_lengths; 271 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 272 } 273 } 274 275 void 276 YoungList::reset_auxilary_lists() { 277 guarantee( is_empty(), "young list should be empty" ); 278 assert(check_list_well_formed(), "young list should be well formed"); 279 280 // Add survivor regions to SurvRateGroup. 281 _g1h->g1_policy()->note_start_adding_survivor_regions(); 282 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 283 284 int young_index_in_cset = 0; 285 for (HeapRegion* curr = _survivor_head; 286 curr != NULL; 287 curr = curr->get_next_young_region()) { 288 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 289 290 // The region is a non-empty survivor so let's add it to 291 // the incremental collection set for the next evacuation 292 // pause. 293 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 294 young_index_in_cset += 1; 295 } 296 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 297 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 298 299 _head = _survivor_head; 300 _length = _survivor_length; 301 if (_survivor_head != NULL) { 302 assert(_survivor_tail != NULL, "cause it shouldn't be"); 303 assert(_survivor_length > 0, "invariant"); 304 _survivor_tail->set_next_young_region(NULL); 305 } 306 307 // Don't clear the survivor list handles until the start of 308 // the next evacuation pause - we need it in order to re-tag 309 // the survivor regions from this evacuation pause as 'young' 310 // at the start of the next. 311 312 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 313 314 assert(check_list_well_formed(), "young list should be well formed"); 315 } 316 317 void YoungList::print() { 318 HeapRegion* lists[] = {_head, _survivor_head}; 319 const char* names[] = {"YOUNG", "SURVIVOR"}; 320 321 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 322 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 323 HeapRegion *curr = lists[list]; 324 if (curr == NULL) 325 gclog_or_tty->print_cr(" empty"); 326 while (curr != NULL) { 327 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 328 HR_FORMAT_PARAMS(curr), 329 p2i(curr->prev_top_at_mark_start()), 330 p2i(curr->next_top_at_mark_start()), 331 curr->age_in_surv_rate_group_cond()); 332 curr = curr->get_next_young_region(); 333 } 334 } 335 336 gclog_or_tty->cr(); 337 } 338 339 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 340 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 341 } 342 343 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 344 // The from card cache is not the memory that is actually committed. So we cannot 345 // take advantage of the zero_filled parameter. 346 reset_from_card_cache(start_idx, num_regions); 347 } 348 349 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 350 { 351 // Claim the right to put the region on the dirty cards region list 352 // by installing a self pointer. 353 HeapRegion* next = hr->get_next_dirty_cards_region(); 354 if (next == NULL) { 355 HeapRegion* res = (HeapRegion*) 356 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 357 NULL); 358 if (res == NULL) { 359 HeapRegion* head; 360 do { 361 // Put the region to the dirty cards region list. 362 head = _dirty_cards_region_list; 363 next = (HeapRegion*) 364 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 365 if (next == head) { 366 assert(hr->get_next_dirty_cards_region() == hr, 367 "hr->get_next_dirty_cards_region() != hr"); 368 if (next == NULL) { 369 // The last region in the list points to itself. 370 hr->set_next_dirty_cards_region(hr); 371 } else { 372 hr->set_next_dirty_cards_region(next); 373 } 374 } 375 } while (next != head); 376 } 377 } 378 } 379 380 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 381 { 382 HeapRegion* head; 383 HeapRegion* hr; 384 do { 385 head = _dirty_cards_region_list; 386 if (head == NULL) { 387 return NULL; 388 } 389 HeapRegion* new_head = head->get_next_dirty_cards_region(); 390 if (head == new_head) { 391 // The last region. 392 new_head = NULL; 393 } 394 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 395 head); 396 } while (hr != head); 397 assert(hr != NULL, "invariant"); 398 hr->set_next_dirty_cards_region(NULL); 399 return hr; 400 } 401 402 // Returns true if the reference points to an object that 403 // can move in an incremental collection. 404 bool G1CollectedHeap::is_scavengable(const void* p) { 405 HeapRegion* hr = heap_region_containing(p); 406 return !hr->is_humongous(); 407 } 408 409 // Private methods. 410 411 HeapRegion* 412 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 413 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 414 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 415 if (!_secondary_free_list.is_empty()) { 416 if (G1ConcRegionFreeingVerbose) { 417 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 418 "secondary_free_list has %u entries", 419 _secondary_free_list.length()); 420 } 421 // It looks as if there are free regions available on the 422 // secondary_free_list. Let's move them to the free_list and try 423 // again to allocate from it. 424 append_secondary_free_list(); 425 426 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 427 "empty we should have moved at least one entry to the free_list"); 428 HeapRegion* res = _hrm.allocate_free_region(is_old); 429 if (G1ConcRegionFreeingVerbose) { 430 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 431 "allocated "HR_FORMAT" from secondary_free_list", 432 HR_FORMAT_PARAMS(res)); 433 } 434 return res; 435 } 436 437 // Wait here until we get notified either when (a) there are no 438 // more free regions coming or (b) some regions have been moved on 439 // the secondary_free_list. 440 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 441 } 442 443 if (G1ConcRegionFreeingVerbose) { 444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 445 "could not allocate from secondary_free_list"); 446 } 447 return NULL; 448 } 449 450 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 451 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 452 "the only time we use this to allocate a humongous region is " 453 "when we are allocating a single humongous region"); 454 455 HeapRegion* res; 456 if (G1StressConcRegionFreeing) { 457 if (!_secondary_free_list.is_empty()) { 458 if (G1ConcRegionFreeingVerbose) { 459 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 460 "forced to look at the secondary_free_list"); 461 } 462 res = new_region_try_secondary_free_list(is_old); 463 if (res != NULL) { 464 return res; 465 } 466 } 467 } 468 469 res = _hrm.allocate_free_region(is_old); 470 471 if (res == NULL) { 472 if (G1ConcRegionFreeingVerbose) { 473 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 474 "res == NULL, trying the secondary_free_list"); 475 } 476 res = new_region_try_secondary_free_list(is_old); 477 } 478 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 479 // Currently, only attempts to allocate GC alloc regions set 480 // do_expand to true. So, we should only reach here during a 481 // safepoint. If this assumption changes we might have to 482 // reconsider the use of _expand_heap_after_alloc_failure. 483 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 484 485 ergo_verbose1(ErgoHeapSizing, 486 "attempt heap expansion", 487 ergo_format_reason("region allocation request failed") 488 ergo_format_byte("allocation request"), 489 word_size * HeapWordSize); 490 if (expand(word_size * HeapWordSize)) { 491 // Given that expand() succeeded in expanding the heap, and we 492 // always expand the heap by an amount aligned to the heap 493 // region size, the free list should in theory not be empty. 494 // In either case allocate_free_region() will check for NULL. 495 res = _hrm.allocate_free_region(is_old); 496 } else { 497 _expand_heap_after_alloc_failure = false; 498 } 499 } 500 return res; 501 } 502 503 HeapWord* 504 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 505 uint num_regions, 506 size_t word_size, 507 AllocationContext_t context) { 508 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 509 assert(is_humongous(word_size), "word_size should be humongous"); 510 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 511 512 // Index of last region in the series + 1. 513 uint last = first + num_regions; 514 515 // We need to initialize the region(s) we just discovered. This is 516 // a bit tricky given that it can happen concurrently with 517 // refinement threads refining cards on these regions and 518 // potentially wanting to refine the BOT as they are scanning 519 // those cards (this can happen shortly after a cleanup; see CR 520 // 6991377). So we have to set up the region(s) carefully and in 521 // a specific order. 522 523 // The word size sum of all the regions we will allocate. 524 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 525 assert(word_size <= word_size_sum, "sanity"); 526 527 // This will be the "starts humongous" region. 528 HeapRegion* first_hr = region_at(first); 529 // The header of the new object will be placed at the bottom of 530 // the first region. 531 HeapWord* new_obj = first_hr->bottom(); 532 // This will be the new end of the first region in the series that 533 // should also match the end of the last region in the series. 534 HeapWord* new_end = new_obj + word_size_sum; 535 // This will be the new top of the first region that will reflect 536 // this allocation. 537 HeapWord* new_top = new_obj + word_size; 538 539 // First, we need to zero the header of the space that we will be 540 // allocating. When we update top further down, some refinement 541 // threads might try to scan the region. By zeroing the header we 542 // ensure that any thread that will try to scan the region will 543 // come across the zero klass word and bail out. 544 // 545 // NOTE: It would not have been correct to have used 546 // CollectedHeap::fill_with_object() and make the space look like 547 // an int array. The thread that is doing the allocation will 548 // later update the object header to a potentially different array 549 // type and, for a very short period of time, the klass and length 550 // fields will be inconsistent. This could cause a refinement 551 // thread to calculate the object size incorrectly. 552 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 553 554 // We will set up the first region as "starts humongous". This 555 // will also update the BOT covering all the regions to reflect 556 // that there is a single object that starts at the bottom of the 557 // first region. 558 first_hr->set_starts_humongous(new_top, new_end); 559 first_hr->set_allocation_context(context); 560 // Then, if there are any, we will set up the "continues 561 // humongous" regions. 562 HeapRegion* hr = NULL; 563 for (uint i = first + 1; i < last; ++i) { 564 hr = region_at(i); 565 hr->set_continues_humongous(first_hr); 566 hr->set_allocation_context(context); 567 } 568 // If we have "continues humongous" regions (hr != NULL), then the 569 // end of the last one should match new_end. 570 assert(hr == NULL || hr->end() == new_end, "sanity"); 571 572 // Up to this point no concurrent thread would have been able to 573 // do any scanning on any region in this series. All the top 574 // fields still point to bottom, so the intersection between 575 // [bottom,top] and [card_start,card_end] will be empty. Before we 576 // update the top fields, we'll do a storestore to make sure that 577 // no thread sees the update to top before the zeroing of the 578 // object header and the BOT initialization. 579 OrderAccess::storestore(); 580 581 // Now that the BOT and the object header have been initialized, 582 // we can update top of the "starts humongous" region. 583 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 584 "new_top should be in this region"); 585 first_hr->set_top(new_top); 586 if (_hr_printer.is_active()) { 587 HeapWord* bottom = first_hr->bottom(); 588 HeapWord* end = first_hr->orig_end(); 589 if ((first + 1) == last) { 590 // the series has a single humongous region 591 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 592 } else { 593 // the series has more than one humongous regions 594 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 595 } 596 } 597 598 // Now, we will update the top fields of the "continues humongous" 599 // regions. The reason we need to do this is that, otherwise, 600 // these regions would look empty and this will confuse parts of 601 // G1. For example, the code that looks for a consecutive number 602 // of empty regions will consider them empty and try to 603 // re-allocate them. We can extend is_empty() to also include 604 // !is_continues_humongous(), but it is easier to just update the top 605 // fields here. The way we set top for all regions (i.e., top == 606 // end for all regions but the last one, top == new_top for the 607 // last one) is actually used when we will free up the humongous 608 // region in free_humongous_region(). 609 hr = NULL; 610 for (uint i = first + 1; i < last; ++i) { 611 hr = region_at(i); 612 if ((i + 1) == last) { 613 // last continues humongous region 614 assert(hr->bottom() < new_top && new_top <= hr->end(), 615 "new_top should fall on this region"); 616 hr->set_top(new_top); 617 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 618 } else { 619 // not last one 620 assert(new_top > hr->end(), "new_top should be above this region"); 621 hr->set_top(hr->end()); 622 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 623 } 624 } 625 // If we have continues humongous regions (hr != NULL), then the 626 // end of the last one should match new_end and its top should 627 // match new_top. 628 assert(hr == NULL || 629 (hr->end() == new_end && hr->top() == new_top), "sanity"); 630 check_bitmaps("Humongous Region Allocation", first_hr); 631 632 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 633 _allocator->increase_used(first_hr->used()); 634 _humongous_set.add(first_hr); 635 636 return new_obj; 637 } 638 639 // If could fit into free regions w/o expansion, try. 640 // Otherwise, if can expand, do so. 641 // Otherwise, if using ex regions might help, try with ex given back. 642 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 644 645 verify_region_sets_optional(); 646 647 uint first = G1_NO_HRM_INDEX; 648 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 649 650 if (obj_regions == 1) { 651 // Only one region to allocate, try to use a fast path by directly allocating 652 // from the free lists. Do not try to expand here, we will potentially do that 653 // later. 654 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 655 if (hr != NULL) { 656 first = hr->hrm_index(); 657 } 658 } else { 659 // We can't allocate humongous regions spanning more than one region while 660 // cleanupComplete() is running, since some of the regions we find to be 661 // empty might not yet be added to the free list. It is not straightforward 662 // to know in which list they are on so that we can remove them. We only 663 // need to do this if we need to allocate more than one region to satisfy the 664 // current humongous allocation request. If we are only allocating one region 665 // we use the one-region region allocation code (see above), that already 666 // potentially waits for regions from the secondary free list. 667 wait_while_free_regions_coming(); 668 append_secondary_free_list_if_not_empty_with_lock(); 669 670 // Policy: Try only empty regions (i.e. already committed first). Maybe we 671 // are lucky enough to find some. 672 first = _hrm.find_contiguous_only_empty(obj_regions); 673 if (first != G1_NO_HRM_INDEX) { 674 _hrm.allocate_free_regions_starting_at(first, obj_regions); 675 } 676 } 677 678 if (first == G1_NO_HRM_INDEX) { 679 // Policy: We could not find enough regions for the humongous object in the 680 // free list. Look through the heap to find a mix of free and uncommitted regions. 681 // If so, try expansion. 682 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 683 if (first != G1_NO_HRM_INDEX) { 684 // We found something. Make sure these regions are committed, i.e. expand 685 // the heap. Alternatively we could do a defragmentation GC. 686 ergo_verbose1(ErgoHeapSizing, 687 "attempt heap expansion", 688 ergo_format_reason("humongous allocation request failed") 689 ergo_format_byte("allocation request"), 690 word_size * HeapWordSize); 691 692 _hrm.expand_at(first, obj_regions); 693 g1_policy()->record_new_heap_size(num_regions()); 694 695 #ifdef ASSERT 696 for (uint i = first; i < first + obj_regions; ++i) { 697 HeapRegion* hr = region_at(i); 698 assert(hr->is_free(), "sanity"); 699 assert(hr->is_empty(), "sanity"); 700 assert(is_on_master_free_list(hr), "sanity"); 701 } 702 #endif 703 _hrm.allocate_free_regions_starting_at(first, obj_regions); 704 } else { 705 // Policy: Potentially trigger a defragmentation GC. 706 } 707 } 708 709 HeapWord* result = NULL; 710 if (first != G1_NO_HRM_INDEX) { 711 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 712 word_size, context); 713 assert(result != NULL, "it should always return a valid result"); 714 715 // A successful humongous object allocation changes the used space 716 // information of the old generation so we need to recalculate the 717 // sizes and update the jstat counters here. 718 g1mm()->update_sizes(); 719 } 720 721 verify_region_sets_optional(); 722 723 return result; 724 } 725 726 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 727 assert_heap_not_locked_and_not_at_safepoint(); 728 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 729 730 uint dummy_gc_count_before; 731 uint dummy_gclocker_retry_count = 0; 732 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 733 } 734 735 HeapWord* 736 G1CollectedHeap::mem_allocate(size_t word_size, 737 bool* gc_overhead_limit_was_exceeded) { 738 assert_heap_not_locked_and_not_at_safepoint(); 739 740 // Loop until the allocation is satisfied, or unsatisfied after GC. 741 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 742 uint gc_count_before; 743 744 HeapWord* result = NULL; 745 if (!is_humongous(word_size)) { 746 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 747 } else { 748 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 749 } 750 if (result != NULL) { 751 return result; 752 } 753 754 // Create the garbage collection operation... 755 VM_G1CollectForAllocation op(gc_count_before, word_size); 756 op.set_allocation_context(AllocationContext::current()); 757 758 // ...and get the VM thread to execute it. 759 VMThread::execute(&op); 760 761 if (op.prologue_succeeded() && op.pause_succeeded()) { 762 // If the operation was successful we'll return the result even 763 // if it is NULL. If the allocation attempt failed immediately 764 // after a Full GC, it's unlikely we'll be able to allocate now. 765 HeapWord* result = op.result(); 766 if (result != NULL && !is_humongous(word_size)) { 767 // Allocations that take place on VM operations do not do any 768 // card dirtying and we have to do it here. We only have to do 769 // this for non-humongous allocations, though. 770 dirty_young_block(result, word_size); 771 } 772 return result; 773 } else { 774 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 775 return NULL; 776 } 777 assert(op.result() == NULL, 778 "the result should be NULL if the VM op did not succeed"); 779 } 780 781 // Give a warning if we seem to be looping forever. 782 if ((QueuedAllocationWarningCount > 0) && 783 (try_count % QueuedAllocationWarningCount == 0)) { 784 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 785 } 786 } 787 788 ShouldNotReachHere(); 789 return NULL; 790 } 791 792 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 793 AllocationContext_t context, 794 uint* gc_count_before_ret, 795 uint* gclocker_retry_count_ret) { 796 // Make sure you read the note in attempt_allocation_humongous(). 797 798 assert_heap_not_locked_and_not_at_safepoint(); 799 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 800 "be called for humongous allocation requests"); 801 802 // We should only get here after the first-level allocation attempt 803 // (attempt_allocation()) failed to allocate. 804 805 // We will loop until a) we manage to successfully perform the 806 // allocation or b) we successfully schedule a collection which 807 // fails to perform the allocation. b) is the only case when we'll 808 // return NULL. 809 HeapWord* result = NULL; 810 for (int try_count = 1; /* we'll return */; try_count += 1) { 811 bool should_try_gc; 812 uint gc_count_before; 813 814 { 815 MutexLockerEx x(Heap_lock); 816 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 817 false /* bot_updates */); 818 if (result != NULL) { 819 return result; 820 } 821 822 // If we reach here, attempt_allocation_locked() above failed to 823 // allocate a new region. So the mutator alloc region should be NULL. 824 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 825 826 if (GC_locker::is_active_and_needs_gc()) { 827 if (g1_policy()->can_expand_young_list()) { 828 // No need for an ergo verbose message here, 829 // can_expand_young_list() does this when it returns true. 830 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 831 false /* bot_updates */); 832 if (result != NULL) { 833 return result; 834 } 835 } 836 should_try_gc = false; 837 } else { 838 // The GCLocker may not be active but the GCLocker initiated 839 // GC may not yet have been performed (GCLocker::needs_gc() 840 // returns true). In this case we do not try this GC and 841 // wait until the GCLocker initiated GC is performed, and 842 // then retry the allocation. 843 if (GC_locker::needs_gc()) { 844 should_try_gc = false; 845 } else { 846 // Read the GC count while still holding the Heap_lock. 847 gc_count_before = total_collections(); 848 should_try_gc = true; 849 } 850 } 851 } 852 853 if (should_try_gc) { 854 bool succeeded; 855 result = do_collection_pause(word_size, gc_count_before, &succeeded, 856 GCCause::_g1_inc_collection_pause); 857 if (result != NULL) { 858 assert(succeeded, "only way to get back a non-NULL result"); 859 return result; 860 } 861 862 if (succeeded) { 863 // If we get here we successfully scheduled a collection which 864 // failed to allocate. No point in trying to allocate 865 // further. We'll just return NULL. 866 MutexLockerEx x(Heap_lock); 867 *gc_count_before_ret = total_collections(); 868 return NULL; 869 } 870 } else { 871 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 872 MutexLockerEx x(Heap_lock); 873 *gc_count_before_ret = total_collections(); 874 return NULL; 875 } 876 // The GCLocker is either active or the GCLocker initiated 877 // GC has not yet been performed. Stall until it is and 878 // then retry the allocation. 879 GC_locker::stall_until_clear(); 880 (*gclocker_retry_count_ret) += 1; 881 } 882 883 // We can reach here if we were unsuccessful in scheduling a 884 // collection (because another thread beat us to it) or if we were 885 // stalled due to the GC locker. In either can we should retry the 886 // allocation attempt in case another thread successfully 887 // performed a collection and reclaimed enough space. We do the 888 // first attempt (without holding the Heap_lock) here and the 889 // follow-on attempt will be at the start of the next loop 890 // iteration (after taking the Heap_lock). 891 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 892 false /* bot_updates */); 893 if (result != NULL) { 894 return result; 895 } 896 897 // Give a warning if we seem to be looping forever. 898 if ((QueuedAllocationWarningCount > 0) && 899 (try_count % QueuedAllocationWarningCount == 0)) { 900 warning("G1CollectedHeap::attempt_allocation_slow() " 901 "retries %d times", try_count); 902 } 903 } 904 905 ShouldNotReachHere(); 906 return NULL; 907 } 908 909 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 910 uint* gc_count_before_ret, 911 uint* gclocker_retry_count_ret) { 912 // The structure of this method has a lot of similarities to 913 // attempt_allocation_slow(). The reason these two were not merged 914 // into a single one is that such a method would require several "if 915 // allocation is not humongous do this, otherwise do that" 916 // conditional paths which would obscure its flow. In fact, an early 917 // version of this code did use a unified method which was harder to 918 // follow and, as a result, it had subtle bugs that were hard to 919 // track down. So keeping these two methods separate allows each to 920 // be more readable. It will be good to keep these two in sync as 921 // much as possible. 922 923 assert_heap_not_locked_and_not_at_safepoint(); 924 assert(is_humongous(word_size), "attempt_allocation_humongous() " 925 "should only be called for humongous allocations"); 926 927 // Humongous objects can exhaust the heap quickly, so we should check if we 928 // need to start a marking cycle at each humongous object allocation. We do 929 // the check before we do the actual allocation. The reason for doing it 930 // before the allocation is that we avoid having to keep track of the newly 931 // allocated memory while we do a GC. 932 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 933 word_size)) { 934 collect(GCCause::_g1_humongous_allocation); 935 } 936 937 // We will loop until a) we manage to successfully perform the 938 // allocation or b) we successfully schedule a collection which 939 // fails to perform the allocation. b) is the only case when we'll 940 // return NULL. 941 HeapWord* result = NULL; 942 for (int try_count = 1; /* we'll return */; try_count += 1) { 943 bool should_try_gc; 944 uint gc_count_before; 945 946 { 947 MutexLockerEx x(Heap_lock); 948 949 // Given that humongous objects are not allocated in young 950 // regions, we'll first try to do the allocation without doing a 951 // collection hoping that there's enough space in the heap. 952 result = humongous_obj_allocate(word_size, AllocationContext::current()); 953 if (result != NULL) { 954 return result; 955 } 956 957 if (GC_locker::is_active_and_needs_gc()) { 958 should_try_gc = false; 959 } else { 960 // The GCLocker may not be active but the GCLocker initiated 961 // GC may not yet have been performed (GCLocker::needs_gc() 962 // returns true). In this case we do not try this GC and 963 // wait until the GCLocker initiated GC is performed, and 964 // then retry the allocation. 965 if (GC_locker::needs_gc()) { 966 should_try_gc = false; 967 } else { 968 // Read the GC count while still holding the Heap_lock. 969 gc_count_before = total_collections(); 970 should_try_gc = true; 971 } 972 } 973 } 974 975 if (should_try_gc) { 976 // If we failed to allocate the humongous object, we should try to 977 // do a collection pause (if we're allowed) in case it reclaims 978 // enough space for the allocation to succeed after the pause. 979 980 bool succeeded; 981 result = do_collection_pause(word_size, gc_count_before, &succeeded, 982 GCCause::_g1_humongous_allocation); 983 if (result != NULL) { 984 assert(succeeded, "only way to get back a non-NULL result"); 985 return result; 986 } 987 988 if (succeeded) { 989 // If we get here we successfully scheduled a collection which 990 // failed to allocate. No point in trying to allocate 991 // further. We'll just return NULL. 992 MutexLockerEx x(Heap_lock); 993 *gc_count_before_ret = total_collections(); 994 return NULL; 995 } 996 } else { 997 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 998 MutexLockerEx x(Heap_lock); 999 *gc_count_before_ret = total_collections(); 1000 return NULL; 1001 } 1002 // The GCLocker is either active or the GCLocker initiated 1003 // GC has not yet been performed. Stall until it is and 1004 // then retry the allocation. 1005 GC_locker::stall_until_clear(); 1006 (*gclocker_retry_count_ret) += 1; 1007 } 1008 1009 // We can reach here if we were unsuccessful in scheduling a 1010 // collection (because another thread beat us to it) or if we were 1011 // stalled due to the GC locker. In either can we should retry the 1012 // allocation attempt in case another thread successfully 1013 // performed a collection and reclaimed enough space. Give a 1014 // warning if we seem to be looping forever. 1015 1016 if ((QueuedAllocationWarningCount > 0) && 1017 (try_count % QueuedAllocationWarningCount == 0)) { 1018 warning("G1CollectedHeap::attempt_allocation_humongous() " 1019 "retries %d times", try_count); 1020 } 1021 } 1022 1023 ShouldNotReachHere(); 1024 return NULL; 1025 } 1026 1027 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1028 AllocationContext_t context, 1029 bool expect_null_mutator_alloc_region) { 1030 assert_at_safepoint(true /* should_be_vm_thread */); 1031 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1032 !expect_null_mutator_alloc_region, 1033 "the current alloc region was unexpectedly found to be non-NULL"); 1034 1035 if (!is_humongous(word_size)) { 1036 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1037 false /* bot_updates */); 1038 } else { 1039 HeapWord* result = humongous_obj_allocate(word_size, context); 1040 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1041 g1_policy()->set_initiate_conc_mark_if_possible(); 1042 } 1043 return result; 1044 } 1045 1046 ShouldNotReachHere(); 1047 } 1048 1049 class PostMCRemSetClearClosure: public HeapRegionClosure { 1050 G1CollectedHeap* _g1h; 1051 ModRefBarrierSet* _mr_bs; 1052 public: 1053 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1054 _g1h(g1h), _mr_bs(mr_bs) {} 1055 1056 bool doHeapRegion(HeapRegion* r) { 1057 HeapRegionRemSet* hrrs = r->rem_set(); 1058 1059 if (r->is_continues_humongous()) { 1060 // We'll assert that the strong code root list and RSet is empty 1061 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1062 assert(hrrs->occupied() == 0, "RSet should be empty"); 1063 return false; 1064 } 1065 1066 _g1h->reset_gc_time_stamps(r); 1067 hrrs->clear(); 1068 // You might think here that we could clear just the cards 1069 // corresponding to the used region. But no: if we leave a dirty card 1070 // in a region we might allocate into, then it would prevent that card 1071 // from being enqueued, and cause it to be missed. 1072 // Re: the performance cost: we shouldn't be doing full GC anyway! 1073 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1074 1075 return false; 1076 } 1077 }; 1078 1079 void G1CollectedHeap::clear_rsets_post_compaction() { 1080 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1081 heap_region_iterate(&rs_clear); 1082 } 1083 1084 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1085 G1CollectedHeap* _g1h; 1086 UpdateRSOopClosure _cl; 1087 int _worker_i; 1088 public: 1089 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1090 _cl(g1->g1_rem_set(), worker_i), 1091 _worker_i(worker_i), 1092 _g1h(g1) 1093 { } 1094 1095 bool doHeapRegion(HeapRegion* r) { 1096 if (!r->is_continues_humongous()) { 1097 _cl.set_from(r); 1098 r->oop_iterate(&_cl); 1099 } 1100 return false; 1101 } 1102 }; 1103 1104 class ParRebuildRSTask: public AbstractGangTask { 1105 G1CollectedHeap* _g1; 1106 HeapRegionClaimer _hrclaimer; 1107 1108 public: 1109 ParRebuildRSTask(G1CollectedHeap* g1) : 1110 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1111 1112 void work(uint worker_id) { 1113 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1114 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1115 } 1116 }; 1117 1118 class PostCompactionPrinterClosure: public HeapRegionClosure { 1119 private: 1120 G1HRPrinter* _hr_printer; 1121 public: 1122 bool doHeapRegion(HeapRegion* hr) { 1123 assert(!hr->is_young(), "not expecting to find young regions"); 1124 if (hr->is_free()) { 1125 // We only generate output for non-empty regions. 1126 } else if (hr->is_starts_humongous()) { 1127 if (hr->region_num() == 1) { 1128 // single humongous region 1129 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1130 } else { 1131 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1132 } 1133 } else if (hr->is_continues_humongous()) { 1134 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1135 } else if (hr->is_old()) { 1136 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1137 } else { 1138 ShouldNotReachHere(); 1139 } 1140 return false; 1141 } 1142 1143 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1144 : _hr_printer(hr_printer) { } 1145 }; 1146 1147 void G1CollectedHeap::print_hrm_post_compaction() { 1148 PostCompactionPrinterClosure cl(hr_printer()); 1149 heap_region_iterate(&cl); 1150 } 1151 1152 bool G1CollectedHeap::do_collection(bool explicit_gc, 1153 bool clear_all_soft_refs, 1154 size_t word_size) { 1155 assert_at_safepoint(true /* should_be_vm_thread */); 1156 1157 if (GC_locker::check_active_before_gc()) { 1158 return false; 1159 } 1160 1161 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1162 gc_timer->register_gc_start(); 1163 1164 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1165 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1166 1167 SvcGCMarker sgcm(SvcGCMarker::FULL); 1168 ResourceMark rm; 1169 1170 print_heap_before_gc(); 1171 trace_heap_before_gc(gc_tracer); 1172 1173 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1174 1175 verify_region_sets_optional(); 1176 1177 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1178 collector_policy()->should_clear_all_soft_refs(); 1179 1180 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1181 1182 { 1183 IsGCActiveMark x; 1184 1185 // Timing 1186 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1187 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1188 1189 { 1190 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1191 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1192 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1193 1194 g1_policy()->record_full_collection_start(); 1195 1196 // Note: When we have a more flexible GC logging framework that 1197 // allows us to add optional attributes to a GC log record we 1198 // could consider timing and reporting how long we wait in the 1199 // following two methods. 1200 wait_while_free_regions_coming(); 1201 // If we start the compaction before the CM threads finish 1202 // scanning the root regions we might trip them over as we'll 1203 // be moving objects / updating references. So let's wait until 1204 // they are done. By telling them to abort, they should complete 1205 // early. 1206 _cm->root_regions()->abort(); 1207 _cm->root_regions()->wait_until_scan_finished(); 1208 append_secondary_free_list_if_not_empty_with_lock(); 1209 1210 gc_prologue(true); 1211 increment_total_collections(true /* full gc */); 1212 increment_old_marking_cycles_started(); 1213 1214 assert(used() == recalculate_used(), "Should be equal"); 1215 1216 verify_before_gc(); 1217 1218 check_bitmaps("Full GC Start"); 1219 pre_full_gc_dump(gc_timer); 1220 1221 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1222 1223 // Disable discovery and empty the discovered lists 1224 // for the CM ref processor. 1225 ref_processor_cm()->disable_discovery(); 1226 ref_processor_cm()->abandon_partial_discovery(); 1227 ref_processor_cm()->verify_no_references_recorded(); 1228 1229 // Abandon current iterations of concurrent marking and concurrent 1230 // refinement, if any are in progress. We have to do this before 1231 // wait_until_scan_finished() below. 1232 concurrent_mark()->abort(); 1233 1234 // Make sure we'll choose a new allocation region afterwards. 1235 _allocator->release_mutator_alloc_region(); 1236 _allocator->abandon_gc_alloc_regions(); 1237 g1_rem_set()->cleanupHRRS(); 1238 1239 // We should call this after we retire any currently active alloc 1240 // regions so that all the ALLOC / RETIRE events are generated 1241 // before the start GC event. 1242 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1243 1244 // We may have added regions to the current incremental collection 1245 // set between the last GC or pause and now. We need to clear the 1246 // incremental collection set and then start rebuilding it afresh 1247 // after this full GC. 1248 abandon_collection_set(g1_policy()->inc_cset_head()); 1249 g1_policy()->clear_incremental_cset(); 1250 g1_policy()->stop_incremental_cset_building(); 1251 1252 tear_down_region_sets(false /* free_list_only */); 1253 g1_policy()->set_gcs_are_young(true); 1254 1255 // See the comments in g1CollectedHeap.hpp and 1256 // G1CollectedHeap::ref_processing_init() about 1257 // how reference processing currently works in G1. 1258 1259 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1260 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1261 1262 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1263 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1264 1265 ref_processor_stw()->enable_discovery(); 1266 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1267 1268 // Do collection work 1269 { 1270 HandleMark hm; // Discard invalid handles created during gc 1271 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1272 } 1273 1274 assert(num_free_regions() == 0, "we should not have added any free regions"); 1275 rebuild_region_sets(false /* free_list_only */); 1276 1277 // Enqueue any discovered reference objects that have 1278 // not been removed from the discovered lists. 1279 ref_processor_stw()->enqueue_discovered_references(); 1280 1281 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1282 1283 MemoryService::track_memory_usage(); 1284 1285 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1286 ref_processor_stw()->verify_no_references_recorded(); 1287 1288 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1289 ClassLoaderDataGraph::purge(); 1290 MetaspaceAux::verify_metrics(); 1291 1292 // Note: since we've just done a full GC, concurrent 1293 // marking is no longer active. Therefore we need not 1294 // re-enable reference discovery for the CM ref processor. 1295 // That will be done at the start of the next marking cycle. 1296 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1297 ref_processor_cm()->verify_no_references_recorded(); 1298 1299 reset_gc_time_stamp(); 1300 // Since everything potentially moved, we will clear all remembered 1301 // sets, and clear all cards. Later we will rebuild remembered 1302 // sets. We will also reset the GC time stamps of the regions. 1303 clear_rsets_post_compaction(); 1304 check_gc_time_stamps(); 1305 1306 // Resize the heap if necessary. 1307 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1308 1309 if (_hr_printer.is_active()) { 1310 // We should do this after we potentially resize the heap so 1311 // that all the COMMIT / UNCOMMIT events are generated before 1312 // the end GC event. 1313 1314 print_hrm_post_compaction(); 1315 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1316 } 1317 1318 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1319 if (hot_card_cache->use_cache()) { 1320 hot_card_cache->reset_card_counts(); 1321 hot_card_cache->reset_hot_cache(); 1322 } 1323 1324 // Rebuild remembered sets of all regions. 1325 uint n_workers = 1326 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1327 workers()->active_workers(), 1328 Threads::number_of_non_daemon_threads()); 1329 assert(UseDynamicNumberOfGCThreads || 1330 n_workers == workers()->total_workers(), 1331 "If not dynamic should be using all the workers"); 1332 workers()->set_active_workers(n_workers); 1333 // Set parallel threads in the heap (_n_par_threads) only 1334 // before a parallel phase and always reset it to 0 after 1335 // the phase so that the number of parallel threads does 1336 // no get carried forward to a serial phase where there 1337 // may be code that is "possibly_parallel". 1338 set_par_threads(n_workers); 1339 1340 ParRebuildRSTask rebuild_rs_task(this); 1341 assert(UseDynamicNumberOfGCThreads || 1342 workers()->active_workers() == workers()->total_workers(), 1343 "Unless dynamic should use total workers"); 1344 // Use the most recent number of active workers 1345 assert(workers()->active_workers() > 0, 1346 "Active workers not properly set"); 1347 set_par_threads(workers()->active_workers()); 1348 workers()->run_task(&rebuild_rs_task); 1349 set_par_threads(0); 1350 1351 // Rebuild the strong code root lists for each region 1352 rebuild_strong_code_roots(); 1353 1354 if (true) { // FIXME 1355 MetaspaceGC::compute_new_size(); 1356 } 1357 1358 #ifdef TRACESPINNING 1359 ParallelTaskTerminator::print_termination_counts(); 1360 #endif 1361 1362 // Discard all rset updates 1363 JavaThread::dirty_card_queue_set().abandon_logs(); 1364 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1365 1366 _young_list->reset_sampled_info(); 1367 // At this point there should be no regions in the 1368 // entire heap tagged as young. 1369 assert(check_young_list_empty(true /* check_heap */), 1370 "young list should be empty at this point"); 1371 1372 // Update the number of full collections that have been completed. 1373 increment_old_marking_cycles_completed(false /* concurrent */); 1374 1375 _hrm.verify_optional(); 1376 verify_region_sets_optional(); 1377 1378 verify_after_gc(); 1379 1380 // Clear the previous marking bitmap, if needed for bitmap verification. 1381 // Note we cannot do this when we clear the next marking bitmap in 1382 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1383 // objects marked during a full GC against the previous bitmap. 1384 // But we need to clear it before calling check_bitmaps below since 1385 // the full GC has compacted objects and updated TAMS but not updated 1386 // the prev bitmap. 1387 if (G1VerifyBitmaps) { 1388 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1389 } 1390 check_bitmaps("Full GC End"); 1391 1392 // Start a new incremental collection set for the next pause 1393 assert(g1_policy()->collection_set() == NULL, "must be"); 1394 g1_policy()->start_incremental_cset_building(); 1395 1396 clear_cset_fast_test(); 1397 1398 _allocator->init_mutator_alloc_region(); 1399 1400 g1_policy()->record_full_collection_end(); 1401 1402 if (G1Log::fine()) { 1403 g1_policy()->print_heap_transition(); 1404 } 1405 1406 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1407 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1408 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1409 // before any GC notifications are raised. 1410 g1mm()->update_sizes(); 1411 1412 gc_epilogue(true); 1413 } 1414 1415 if (G1Log::finer()) { 1416 g1_policy()->print_detailed_heap_transition(true /* full */); 1417 } 1418 1419 print_heap_after_gc(); 1420 trace_heap_after_gc(gc_tracer); 1421 1422 post_full_gc_dump(gc_timer); 1423 1424 gc_timer->register_gc_end(); 1425 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1426 } 1427 1428 return true; 1429 } 1430 1431 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1432 // do_collection() will return whether it succeeded in performing 1433 // the GC. Currently, there is no facility on the 1434 // do_full_collection() API to notify the caller than the collection 1435 // did not succeed (e.g., because it was locked out by the GC 1436 // locker). So, right now, we'll ignore the return value. 1437 bool dummy = do_collection(true, /* explicit_gc */ 1438 clear_all_soft_refs, 1439 0 /* word_size */); 1440 } 1441 1442 // This code is mostly copied from TenuredGeneration. 1443 void 1444 G1CollectedHeap:: 1445 resize_if_necessary_after_full_collection(size_t word_size) { 1446 // Include the current allocation, if any, and bytes that will be 1447 // pre-allocated to support collections, as "used". 1448 const size_t used_after_gc = used(); 1449 const size_t capacity_after_gc = capacity(); 1450 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1451 1452 // This is enforced in arguments.cpp. 1453 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1454 "otherwise the code below doesn't make sense"); 1455 1456 // We don't have floating point command-line arguments 1457 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1458 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1459 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1460 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1461 1462 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1463 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1464 1465 // We have to be careful here as these two calculations can overflow 1466 // 32-bit size_t's. 1467 double used_after_gc_d = (double) used_after_gc; 1468 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1469 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1470 1471 // Let's make sure that they are both under the max heap size, which 1472 // by default will make them fit into a size_t. 1473 double desired_capacity_upper_bound = (double) max_heap_size; 1474 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1475 desired_capacity_upper_bound); 1476 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1477 desired_capacity_upper_bound); 1478 1479 // We can now safely turn them into size_t's. 1480 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1481 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1482 1483 // This assert only makes sense here, before we adjust them 1484 // with respect to the min and max heap size. 1485 assert(minimum_desired_capacity <= maximum_desired_capacity, 1486 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1487 "maximum_desired_capacity = "SIZE_FORMAT, 1488 minimum_desired_capacity, maximum_desired_capacity)); 1489 1490 // Should not be greater than the heap max size. No need to adjust 1491 // it with respect to the heap min size as it's a lower bound (i.e., 1492 // we'll try to make the capacity larger than it, not smaller). 1493 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1494 // Should not be less than the heap min size. No need to adjust it 1495 // with respect to the heap max size as it's an upper bound (i.e., 1496 // we'll try to make the capacity smaller than it, not greater). 1497 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1498 1499 if (capacity_after_gc < minimum_desired_capacity) { 1500 // Don't expand unless it's significant 1501 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1502 ergo_verbose4(ErgoHeapSizing, 1503 "attempt heap expansion", 1504 ergo_format_reason("capacity lower than " 1505 "min desired capacity after Full GC") 1506 ergo_format_byte("capacity") 1507 ergo_format_byte("occupancy") 1508 ergo_format_byte_perc("min desired capacity"), 1509 capacity_after_gc, used_after_gc, 1510 minimum_desired_capacity, (double) MinHeapFreeRatio); 1511 expand(expand_bytes); 1512 1513 // No expansion, now see if we want to shrink 1514 } else if (capacity_after_gc > maximum_desired_capacity) { 1515 // Capacity too large, compute shrinking size 1516 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1517 ergo_verbose4(ErgoHeapSizing, 1518 "attempt heap shrinking", 1519 ergo_format_reason("capacity higher than " 1520 "max desired capacity after Full GC") 1521 ergo_format_byte("capacity") 1522 ergo_format_byte("occupancy") 1523 ergo_format_byte_perc("max desired capacity"), 1524 capacity_after_gc, used_after_gc, 1525 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1526 shrink(shrink_bytes); 1527 } 1528 } 1529 1530 1531 HeapWord* 1532 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1533 AllocationContext_t context, 1534 bool* succeeded) { 1535 assert_at_safepoint(true /* should_be_vm_thread */); 1536 1537 *succeeded = true; 1538 // Let's attempt the allocation first. 1539 HeapWord* result = 1540 attempt_allocation_at_safepoint(word_size, 1541 context, 1542 false /* expect_null_mutator_alloc_region */); 1543 if (result != NULL) { 1544 assert(*succeeded, "sanity"); 1545 return result; 1546 } 1547 1548 // In a G1 heap, we're supposed to keep allocation from failing by 1549 // incremental pauses. Therefore, at least for now, we'll favor 1550 // expansion over collection. (This might change in the future if we can 1551 // do something smarter than full collection to satisfy a failed alloc.) 1552 result = expand_and_allocate(word_size, context); 1553 if (result != NULL) { 1554 assert(*succeeded, "sanity"); 1555 return result; 1556 } 1557 1558 // Expansion didn't work, we'll try to do a Full GC. 1559 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1560 false, /* clear_all_soft_refs */ 1561 word_size); 1562 if (!gc_succeeded) { 1563 *succeeded = false; 1564 return NULL; 1565 } 1566 1567 // Retry the allocation 1568 result = attempt_allocation_at_safepoint(word_size, 1569 context, 1570 true /* expect_null_mutator_alloc_region */); 1571 if (result != NULL) { 1572 assert(*succeeded, "sanity"); 1573 return result; 1574 } 1575 1576 // Then, try a Full GC that will collect all soft references. 1577 gc_succeeded = do_collection(false, /* explicit_gc */ 1578 true, /* clear_all_soft_refs */ 1579 word_size); 1580 if (!gc_succeeded) { 1581 *succeeded = false; 1582 return NULL; 1583 } 1584 1585 // Retry the allocation once more 1586 result = attempt_allocation_at_safepoint(word_size, 1587 context, 1588 true /* expect_null_mutator_alloc_region */); 1589 if (result != NULL) { 1590 assert(*succeeded, "sanity"); 1591 return result; 1592 } 1593 1594 assert(!collector_policy()->should_clear_all_soft_refs(), 1595 "Flag should have been handled and cleared prior to this point"); 1596 1597 // What else? We might try synchronous finalization later. If the total 1598 // space available is large enough for the allocation, then a more 1599 // complete compaction phase than we've tried so far might be 1600 // appropriate. 1601 assert(*succeeded, "sanity"); 1602 return NULL; 1603 } 1604 1605 // Attempting to expand the heap sufficiently 1606 // to support an allocation of the given "word_size". If 1607 // successful, perform the allocation and return the address of the 1608 // allocated block, or else "NULL". 1609 1610 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1611 assert_at_safepoint(true /* should_be_vm_thread */); 1612 1613 verify_region_sets_optional(); 1614 1615 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1616 ergo_verbose1(ErgoHeapSizing, 1617 "attempt heap expansion", 1618 ergo_format_reason("allocation request failed") 1619 ergo_format_byte("allocation request"), 1620 word_size * HeapWordSize); 1621 if (expand(expand_bytes)) { 1622 _hrm.verify_optional(); 1623 verify_region_sets_optional(); 1624 return attempt_allocation_at_safepoint(word_size, 1625 context, 1626 false /* expect_null_mutator_alloc_region */); 1627 } 1628 return NULL; 1629 } 1630 1631 bool G1CollectedHeap::expand(size_t expand_bytes) { 1632 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1633 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1634 HeapRegion::GrainBytes); 1635 ergo_verbose2(ErgoHeapSizing, 1636 "expand the heap", 1637 ergo_format_byte("requested expansion amount") 1638 ergo_format_byte("attempted expansion amount"), 1639 expand_bytes, aligned_expand_bytes); 1640 1641 if (is_maximal_no_gc()) { 1642 ergo_verbose0(ErgoHeapSizing, 1643 "did not expand the heap", 1644 ergo_format_reason("heap already fully expanded")); 1645 return false; 1646 } 1647 1648 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1649 assert(regions_to_expand > 0, "Must expand by at least one region"); 1650 1651 uint expanded_by = _hrm.expand_by(regions_to_expand); 1652 1653 if (expanded_by > 0) { 1654 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1655 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1656 g1_policy()->record_new_heap_size(num_regions()); 1657 } else { 1658 ergo_verbose0(ErgoHeapSizing, 1659 "did not expand the heap", 1660 ergo_format_reason("heap expansion operation failed")); 1661 // The expansion of the virtual storage space was unsuccessful. 1662 // Let's see if it was because we ran out of swap. 1663 if (G1ExitOnExpansionFailure && 1664 _hrm.available() >= regions_to_expand) { 1665 // We had head room... 1666 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1667 } 1668 } 1669 return regions_to_expand > 0; 1670 } 1671 1672 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1673 size_t aligned_shrink_bytes = 1674 ReservedSpace::page_align_size_down(shrink_bytes); 1675 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1676 HeapRegion::GrainBytes); 1677 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1678 1679 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1680 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1681 1682 ergo_verbose3(ErgoHeapSizing, 1683 "shrink the heap", 1684 ergo_format_byte("requested shrinking amount") 1685 ergo_format_byte("aligned shrinking amount") 1686 ergo_format_byte("attempted shrinking amount"), 1687 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1688 if (num_regions_removed > 0) { 1689 g1_policy()->record_new_heap_size(num_regions()); 1690 } else { 1691 ergo_verbose0(ErgoHeapSizing, 1692 "did not shrink the heap", 1693 ergo_format_reason("heap shrinking operation failed")); 1694 } 1695 } 1696 1697 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1698 verify_region_sets_optional(); 1699 1700 // We should only reach here at the end of a Full GC which means we 1701 // should not not be holding to any GC alloc regions. The method 1702 // below will make sure of that and do any remaining clean up. 1703 _allocator->abandon_gc_alloc_regions(); 1704 1705 // Instead of tearing down / rebuilding the free lists here, we 1706 // could instead use the remove_all_pending() method on free_list to 1707 // remove only the ones that we need to remove. 1708 tear_down_region_sets(true /* free_list_only */); 1709 shrink_helper(shrink_bytes); 1710 rebuild_region_sets(true /* free_list_only */); 1711 1712 _hrm.verify_optional(); 1713 verify_region_sets_optional(); 1714 } 1715 1716 // Public methods. 1717 1718 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1719 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1720 #endif // _MSC_VER 1721 1722 1723 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1724 CollectedHeap(), 1725 _g1_policy(policy_), 1726 _dirty_card_queue_set(false), 1727 _into_cset_dirty_card_queue_set(false), 1728 _is_alive_closure_cm(this), 1729 _is_alive_closure_stw(this), 1730 _ref_processor_cm(NULL), 1731 _ref_processor_stw(NULL), 1732 _bot_shared(NULL), 1733 _evac_failure_scan_stack(NULL), 1734 _mark_in_progress(false), 1735 _cg1r(NULL), 1736 _g1mm(NULL), 1737 _refine_cte_cl(NULL), 1738 _full_collection(false), 1739 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1740 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1741 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1742 _humongous_reclaim_candidates(), 1743 _has_humongous_reclaim_candidates(false), 1744 _free_regions_coming(false), 1745 _young_list(new YoungList(this)), 1746 _gc_time_stamp(0), 1747 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1748 _old_plab_stats(OldPLABSize, PLABWeight), 1749 _expand_heap_after_alloc_failure(true), 1750 _surviving_young_words(NULL), 1751 _old_marking_cycles_started(0), 1752 _old_marking_cycles_completed(0), 1753 _concurrent_cycle_started(false), 1754 _heap_summary_sent(false), 1755 _in_cset_fast_test(), 1756 _dirty_cards_region_list(NULL), 1757 _worker_cset_start_region(NULL), 1758 _worker_cset_start_region_time_stamp(NULL), 1759 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1760 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1761 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1762 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1763 1764 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 1765 /* are_GC_task_threads */true, 1766 /* are_ConcurrentGC_threads */false); 1767 _workers->initialize_workers(); 1768 1769 _allocator = G1Allocator::create_allocator(this); 1770 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1771 1772 int n_queues = MAX2((int)ParallelGCThreads, 1); 1773 _task_queues = new RefToScanQueueSet(n_queues); 1774 1775 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1776 assert(n_rem_sets > 0, "Invariant."); 1777 1778 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1779 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1780 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1781 1782 for (int i = 0; i < n_queues; i++) { 1783 RefToScanQueue* q = new RefToScanQueue(); 1784 q->initialize(); 1785 _task_queues->register_queue(i, q); 1786 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1787 } 1788 clear_cset_start_regions(); 1789 1790 // Initialize the G1EvacuationFailureALot counters and flags. 1791 NOT_PRODUCT(reset_evacuation_should_fail();) 1792 1793 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1794 } 1795 1796 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1797 size_t size, 1798 size_t translation_factor) { 1799 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1800 // Allocate a new reserved space, preferring to use large pages. 1801 ReservedSpace rs(size, preferred_page_size); 1802 G1RegionToSpaceMapper* result = 1803 G1RegionToSpaceMapper::create_mapper(rs, 1804 size, 1805 rs.alignment(), 1806 HeapRegion::GrainBytes, 1807 translation_factor, 1808 mtGC); 1809 if (TracePageSizes) { 1810 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1811 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1812 } 1813 return result; 1814 } 1815 1816 jint G1CollectedHeap::initialize() { 1817 CollectedHeap::pre_initialize(); 1818 os::enable_vtime(); 1819 1820 G1Log::init(); 1821 1822 // Necessary to satisfy locking discipline assertions. 1823 1824 MutexLocker x(Heap_lock); 1825 1826 // We have to initialize the printer before committing the heap, as 1827 // it will be used then. 1828 _hr_printer.set_active(G1PrintHeapRegions); 1829 1830 // While there are no constraints in the GC code that HeapWordSize 1831 // be any particular value, there are multiple other areas in the 1832 // system which believe this to be true (e.g. oop->object_size in some 1833 // cases incorrectly returns the size in wordSize units rather than 1834 // HeapWordSize). 1835 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1836 1837 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1838 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1839 size_t heap_alignment = collector_policy()->heap_alignment(); 1840 1841 // Ensure that the sizes are properly aligned. 1842 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1843 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1844 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1845 1846 _refine_cte_cl = new RefineCardTableEntryClosure(); 1847 1848 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1849 1850 // Reserve the maximum. 1851 1852 // When compressed oops are enabled, the preferred heap base 1853 // is calculated by subtracting the requested size from the 1854 // 32Gb boundary and using the result as the base address for 1855 // heap reservation. If the requested size is not aligned to 1856 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1857 // into the ReservedHeapSpace constructor) then the actual 1858 // base of the reserved heap may end up differing from the 1859 // address that was requested (i.e. the preferred heap base). 1860 // If this happens then we could end up using a non-optimal 1861 // compressed oops mode. 1862 1863 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1864 heap_alignment); 1865 1866 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1867 1868 // Create the barrier set for the entire reserved region. 1869 G1SATBCardTableLoggingModRefBS* bs 1870 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1871 bs->initialize(); 1872 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1873 set_barrier_set(bs); 1874 1875 // Also create a G1 rem set. 1876 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1877 1878 // Carve out the G1 part of the heap. 1879 1880 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1881 G1RegionToSpaceMapper* heap_storage = 1882 G1RegionToSpaceMapper::create_mapper(g1_rs, 1883 g1_rs.size(), 1884 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1885 HeapRegion::GrainBytes, 1886 1, 1887 mtJavaHeap); 1888 heap_storage->set_mapping_changed_listener(&_listener); 1889 1890 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1891 G1RegionToSpaceMapper* bot_storage = 1892 create_aux_memory_mapper("Block offset table", 1893 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1894 G1BlockOffsetSharedArray::N_bytes); 1895 1896 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1897 G1RegionToSpaceMapper* cardtable_storage = 1898 create_aux_memory_mapper("Card table", 1899 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1900 G1BlockOffsetSharedArray::N_bytes); 1901 1902 G1RegionToSpaceMapper* card_counts_storage = 1903 create_aux_memory_mapper("Card counts table", 1904 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1905 G1BlockOffsetSharedArray::N_bytes); 1906 1907 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1908 G1RegionToSpaceMapper* prev_bitmap_storage = 1909 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance()); 1910 G1RegionToSpaceMapper* next_bitmap_storage = 1911 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance()); 1912 1913 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1914 g1_barrier_set()->initialize(cardtable_storage); 1915 // Do later initialization work for concurrent refinement. 1916 _cg1r->init(card_counts_storage); 1917 1918 // 6843694 - ensure that the maximum region index can fit 1919 // in the remembered set structures. 1920 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1921 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1922 1923 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1924 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1925 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1926 "too many cards per region"); 1927 1928 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1929 1930 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1931 1932 { 1933 HeapWord* start = _hrm.reserved().start(); 1934 HeapWord* end = _hrm.reserved().end(); 1935 size_t granularity = HeapRegion::GrainBytes; 1936 1937 _in_cset_fast_test.initialize(start, end, granularity); 1938 _humongous_reclaim_candidates.initialize(start, end, granularity); 1939 } 1940 1941 // Create the ConcurrentMark data structure and thread. 1942 // (Must do this late, so that "max_regions" is defined.) 1943 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1944 if (_cm == NULL || !_cm->completed_initialization()) { 1945 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1946 return JNI_ENOMEM; 1947 } 1948 _cmThread = _cm->cmThread(); 1949 1950 // Initialize the from_card cache structure of HeapRegionRemSet. 1951 HeapRegionRemSet::init_heap(max_regions()); 1952 1953 // Now expand into the initial heap size. 1954 if (!expand(init_byte_size)) { 1955 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1956 return JNI_ENOMEM; 1957 } 1958 1959 // Perform any initialization actions delegated to the policy. 1960 g1_policy()->init(); 1961 1962 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1963 SATB_Q_FL_lock, 1964 G1SATBProcessCompletedThreshold, 1965 Shared_SATB_Q_lock); 1966 1967 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1968 DirtyCardQ_CBL_mon, 1969 DirtyCardQ_FL_lock, 1970 concurrent_g1_refine()->yellow_zone(), 1971 concurrent_g1_refine()->red_zone(), 1972 Shared_DirtyCardQ_lock); 1973 1974 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1975 DirtyCardQ_CBL_mon, 1976 DirtyCardQ_FL_lock, 1977 -1, // never trigger processing 1978 -1, // no limit on length 1979 Shared_DirtyCardQ_lock, 1980 &JavaThread::dirty_card_queue_set()); 1981 1982 // Initialize the card queue set used to hold cards containing 1983 // references into the collection set. 1984 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 1985 DirtyCardQ_CBL_mon, 1986 DirtyCardQ_FL_lock, 1987 -1, // never trigger processing 1988 -1, // no limit on length 1989 Shared_DirtyCardQ_lock, 1990 &JavaThread::dirty_card_queue_set()); 1991 1992 // Here we allocate the dummy HeapRegion that is required by the 1993 // G1AllocRegion class. 1994 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1995 1996 // We'll re-use the same region whether the alloc region will 1997 // require BOT updates or not and, if it doesn't, then a non-young 1998 // region will complain that it cannot support allocations without 1999 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2000 dummy_region->set_eden(); 2001 // Make sure it's full. 2002 dummy_region->set_top(dummy_region->end()); 2003 G1AllocRegion::setup(this, dummy_region); 2004 2005 _allocator->init_mutator_alloc_region(); 2006 2007 // Do create of the monitoring and management support so that 2008 // values in the heap have been properly initialized. 2009 _g1mm = new G1MonitoringSupport(this); 2010 2011 G1StringDedup::initialize(); 2012 2013 return JNI_OK; 2014 } 2015 2016 void G1CollectedHeap::stop() { 2017 // Stop all concurrent threads. We do this to make sure these threads 2018 // do not continue to execute and access resources (e.g. gclog_or_tty) 2019 // that are destroyed during shutdown. 2020 _cg1r->stop(); 2021 _cmThread->stop(); 2022 if (G1StringDedup::is_enabled()) { 2023 G1StringDedup::stop(); 2024 } 2025 } 2026 2027 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2028 return HeapRegion::max_region_size(); 2029 } 2030 2031 void G1CollectedHeap::post_initialize() { 2032 CollectedHeap::post_initialize(); 2033 ref_processing_init(); 2034 } 2035 2036 void G1CollectedHeap::ref_processing_init() { 2037 // Reference processing in G1 currently works as follows: 2038 // 2039 // * There are two reference processor instances. One is 2040 // used to record and process discovered references 2041 // during concurrent marking; the other is used to 2042 // record and process references during STW pauses 2043 // (both full and incremental). 2044 // * Both ref processors need to 'span' the entire heap as 2045 // the regions in the collection set may be dotted around. 2046 // 2047 // * For the concurrent marking ref processor: 2048 // * Reference discovery is enabled at initial marking. 2049 // * Reference discovery is disabled and the discovered 2050 // references processed etc during remarking. 2051 // * Reference discovery is MT (see below). 2052 // * Reference discovery requires a barrier (see below). 2053 // * Reference processing may or may not be MT 2054 // (depending on the value of ParallelRefProcEnabled 2055 // and ParallelGCThreads). 2056 // * A full GC disables reference discovery by the CM 2057 // ref processor and abandons any entries on it's 2058 // discovered lists. 2059 // 2060 // * For the STW processor: 2061 // * Non MT discovery is enabled at the start of a full GC. 2062 // * Processing and enqueueing during a full GC is non-MT. 2063 // * During a full GC, references are processed after marking. 2064 // 2065 // * Discovery (may or may not be MT) is enabled at the start 2066 // of an incremental evacuation pause. 2067 // * References are processed near the end of a STW evacuation pause. 2068 // * For both types of GC: 2069 // * Discovery is atomic - i.e. not concurrent. 2070 // * Reference discovery will not need a barrier. 2071 2072 MemRegion mr = reserved_region(); 2073 2074 // Concurrent Mark ref processor 2075 _ref_processor_cm = 2076 new ReferenceProcessor(mr, // span 2077 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2078 // mt processing 2079 (int) ParallelGCThreads, 2080 // degree of mt processing 2081 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2082 // mt discovery 2083 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2084 // degree of mt discovery 2085 false, 2086 // Reference discovery is not atomic 2087 &_is_alive_closure_cm); 2088 // is alive closure 2089 // (for efficiency/performance) 2090 2091 // STW ref processor 2092 _ref_processor_stw = 2093 new ReferenceProcessor(mr, // span 2094 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2095 // mt processing 2096 MAX2((int)ParallelGCThreads, 1), 2097 // degree of mt processing 2098 (ParallelGCThreads > 1), 2099 // mt discovery 2100 MAX2((int)ParallelGCThreads, 1), 2101 // degree of mt discovery 2102 true, 2103 // Reference discovery is atomic 2104 &_is_alive_closure_stw); 2105 // is alive closure 2106 // (for efficiency/performance) 2107 } 2108 2109 size_t G1CollectedHeap::capacity() const { 2110 return _hrm.length() * HeapRegion::GrainBytes; 2111 } 2112 2113 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2114 assert(!hr->is_continues_humongous(), "pre-condition"); 2115 hr->reset_gc_time_stamp(); 2116 if (hr->is_starts_humongous()) { 2117 uint first_index = hr->hrm_index() + 1; 2118 uint last_index = hr->last_hc_index(); 2119 for (uint i = first_index; i < last_index; i += 1) { 2120 HeapRegion* chr = region_at(i); 2121 assert(chr->is_continues_humongous(), "sanity"); 2122 chr->reset_gc_time_stamp(); 2123 } 2124 } 2125 } 2126 2127 #ifndef PRODUCT 2128 2129 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2130 private: 2131 unsigned _gc_time_stamp; 2132 bool _failures; 2133 2134 public: 2135 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2136 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2137 2138 virtual bool doHeapRegion(HeapRegion* hr) { 2139 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2140 if (_gc_time_stamp != region_gc_time_stamp) { 2141 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2142 "expected %d", HR_FORMAT_PARAMS(hr), 2143 region_gc_time_stamp, _gc_time_stamp); 2144 _failures = true; 2145 } 2146 return false; 2147 } 2148 2149 bool failures() { return _failures; } 2150 }; 2151 2152 void G1CollectedHeap::check_gc_time_stamps() { 2153 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2154 heap_region_iterate(&cl); 2155 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2156 } 2157 #endif // PRODUCT 2158 2159 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2160 DirtyCardQueue* into_cset_dcq, 2161 bool concurrent, 2162 uint worker_i) { 2163 // Clean cards in the hot card cache 2164 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2165 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2166 2167 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2168 size_t n_completed_buffers = 0; 2169 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2170 n_completed_buffers++; 2171 } 2172 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2173 dcqs.clear_n_completed_buffers(); 2174 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2175 } 2176 2177 2178 // Computes the sum of the storage used by the various regions. 2179 size_t G1CollectedHeap::used() const { 2180 return _allocator->used(); 2181 } 2182 2183 size_t G1CollectedHeap::used_unlocked() const { 2184 return _allocator->used_unlocked(); 2185 } 2186 2187 class SumUsedClosure: public HeapRegionClosure { 2188 size_t _used; 2189 public: 2190 SumUsedClosure() : _used(0) {} 2191 bool doHeapRegion(HeapRegion* r) { 2192 if (!r->is_continues_humongous()) { 2193 _used += r->used(); 2194 } 2195 return false; 2196 } 2197 size_t result() { return _used; } 2198 }; 2199 2200 size_t G1CollectedHeap::recalculate_used() const { 2201 double recalculate_used_start = os::elapsedTime(); 2202 2203 SumUsedClosure blk; 2204 heap_region_iterate(&blk); 2205 2206 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2207 return blk.result(); 2208 } 2209 2210 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2211 switch (cause) { 2212 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2213 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2214 case GCCause::_g1_humongous_allocation: return true; 2215 case GCCause::_update_allocation_context_stats_inc: return true; 2216 case GCCause::_wb_conc_mark: return true; 2217 default: return false; 2218 } 2219 } 2220 2221 #ifndef PRODUCT 2222 void G1CollectedHeap::allocate_dummy_regions() { 2223 // Let's fill up most of the region 2224 size_t word_size = HeapRegion::GrainWords - 1024; 2225 // And as a result the region we'll allocate will be humongous. 2226 guarantee(is_humongous(word_size), "sanity"); 2227 2228 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2229 // Let's use the existing mechanism for the allocation 2230 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2231 AllocationContext::system()); 2232 if (dummy_obj != NULL) { 2233 MemRegion mr(dummy_obj, word_size); 2234 CollectedHeap::fill_with_object(mr); 2235 } else { 2236 // If we can't allocate once, we probably cannot allocate 2237 // again. Let's get out of the loop. 2238 break; 2239 } 2240 } 2241 } 2242 #endif // !PRODUCT 2243 2244 void G1CollectedHeap::increment_old_marking_cycles_started() { 2245 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2246 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2247 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2248 _old_marking_cycles_started, _old_marking_cycles_completed)); 2249 2250 _old_marking_cycles_started++; 2251 } 2252 2253 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2254 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2255 2256 // We assume that if concurrent == true, then the caller is a 2257 // concurrent thread that was joined the Suspendible Thread 2258 // Set. If there's ever a cheap way to check this, we should add an 2259 // assert here. 2260 2261 // Given that this method is called at the end of a Full GC or of a 2262 // concurrent cycle, and those can be nested (i.e., a Full GC can 2263 // interrupt a concurrent cycle), the number of full collections 2264 // completed should be either one (in the case where there was no 2265 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2266 // behind the number of full collections started. 2267 2268 // This is the case for the inner caller, i.e. a Full GC. 2269 assert(concurrent || 2270 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2271 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2272 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2273 "is inconsistent with _old_marking_cycles_completed = %u", 2274 _old_marking_cycles_started, _old_marking_cycles_completed)); 2275 2276 // This is the case for the outer caller, i.e. the concurrent cycle. 2277 assert(!concurrent || 2278 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2279 err_msg("for outer caller (concurrent cycle): " 2280 "_old_marking_cycles_started = %u " 2281 "is inconsistent with _old_marking_cycles_completed = %u", 2282 _old_marking_cycles_started, _old_marking_cycles_completed)); 2283 2284 _old_marking_cycles_completed += 1; 2285 2286 // We need to clear the "in_progress" flag in the CM thread before 2287 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2288 // is set) so that if a waiter requests another System.gc() it doesn't 2289 // incorrectly see that a marking cycle is still in progress. 2290 if (concurrent) { 2291 _cmThread->clear_in_progress(); 2292 } 2293 2294 // This notify_all() will ensure that a thread that called 2295 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2296 // and it's waiting for a full GC to finish will be woken up. It is 2297 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2298 FullGCCount_lock->notify_all(); 2299 } 2300 2301 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2302 _concurrent_cycle_started = true; 2303 _gc_timer_cm->register_gc_start(start_time); 2304 2305 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2306 trace_heap_before_gc(_gc_tracer_cm); 2307 } 2308 2309 void G1CollectedHeap::register_concurrent_cycle_end() { 2310 if (_concurrent_cycle_started) { 2311 if (_cm->has_aborted()) { 2312 _gc_tracer_cm->report_concurrent_mode_failure(); 2313 } 2314 2315 _gc_timer_cm->register_gc_end(); 2316 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2317 2318 // Clear state variables to prepare for the next concurrent cycle. 2319 _concurrent_cycle_started = false; 2320 _heap_summary_sent = false; 2321 } 2322 } 2323 2324 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2325 if (_concurrent_cycle_started) { 2326 // This function can be called when: 2327 // the cleanup pause is run 2328 // the concurrent cycle is aborted before the cleanup pause. 2329 // the concurrent cycle is aborted after the cleanup pause, 2330 // but before the concurrent cycle end has been registered. 2331 // Make sure that we only send the heap information once. 2332 if (!_heap_summary_sent) { 2333 trace_heap_after_gc(_gc_tracer_cm); 2334 _heap_summary_sent = true; 2335 } 2336 } 2337 } 2338 2339 G1YCType G1CollectedHeap::yc_type() { 2340 bool is_young = g1_policy()->gcs_are_young(); 2341 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2342 bool is_during_mark = mark_in_progress(); 2343 2344 if (is_initial_mark) { 2345 return InitialMark; 2346 } else if (is_during_mark) { 2347 return DuringMark; 2348 } else if (is_young) { 2349 return Normal; 2350 } else { 2351 return Mixed; 2352 } 2353 } 2354 2355 void G1CollectedHeap::collect(GCCause::Cause cause) { 2356 assert_heap_not_locked(); 2357 2358 uint gc_count_before; 2359 uint old_marking_count_before; 2360 uint full_gc_count_before; 2361 bool retry_gc; 2362 2363 do { 2364 retry_gc = false; 2365 2366 { 2367 MutexLocker ml(Heap_lock); 2368 2369 // Read the GC count while holding the Heap_lock 2370 gc_count_before = total_collections(); 2371 full_gc_count_before = total_full_collections(); 2372 old_marking_count_before = _old_marking_cycles_started; 2373 } 2374 2375 if (should_do_concurrent_full_gc(cause)) { 2376 // Schedule an initial-mark evacuation pause that will start a 2377 // concurrent cycle. We're setting word_size to 0 which means that 2378 // we are not requesting a post-GC allocation. 2379 VM_G1IncCollectionPause op(gc_count_before, 2380 0, /* word_size */ 2381 true, /* should_initiate_conc_mark */ 2382 g1_policy()->max_pause_time_ms(), 2383 cause); 2384 op.set_allocation_context(AllocationContext::current()); 2385 2386 VMThread::execute(&op); 2387 if (!op.pause_succeeded()) { 2388 if (old_marking_count_before == _old_marking_cycles_started) { 2389 retry_gc = op.should_retry_gc(); 2390 } else { 2391 // A Full GC happened while we were trying to schedule the 2392 // initial-mark GC. No point in starting a new cycle given 2393 // that the whole heap was collected anyway. 2394 } 2395 2396 if (retry_gc) { 2397 if (GC_locker::is_active_and_needs_gc()) { 2398 GC_locker::stall_until_clear(); 2399 } 2400 } 2401 } 2402 } else { 2403 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2404 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2405 2406 // Schedule a standard evacuation pause. We're setting word_size 2407 // to 0 which means that we are not requesting a post-GC allocation. 2408 VM_G1IncCollectionPause op(gc_count_before, 2409 0, /* word_size */ 2410 false, /* should_initiate_conc_mark */ 2411 g1_policy()->max_pause_time_ms(), 2412 cause); 2413 VMThread::execute(&op); 2414 } else { 2415 // Schedule a Full GC. 2416 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2417 VMThread::execute(&op); 2418 } 2419 } 2420 } while (retry_gc); 2421 } 2422 2423 bool G1CollectedHeap::is_in(const void* p) const { 2424 if (_hrm.reserved().contains(p)) { 2425 // Given that we know that p is in the reserved space, 2426 // heap_region_containing_raw() should successfully 2427 // return the containing region. 2428 HeapRegion* hr = heap_region_containing_raw(p); 2429 return hr->is_in(p); 2430 } else { 2431 return false; 2432 } 2433 } 2434 2435 #ifdef ASSERT 2436 bool G1CollectedHeap::is_in_exact(const void* p) const { 2437 bool contains = reserved_region().contains(p); 2438 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2439 if (contains && available) { 2440 return true; 2441 } else { 2442 return false; 2443 } 2444 } 2445 #endif 2446 2447 // Iteration functions. 2448 2449 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2450 2451 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2452 ExtendedOopClosure* _cl; 2453 public: 2454 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2455 bool doHeapRegion(HeapRegion* r) { 2456 if (!r->is_continues_humongous()) { 2457 r->oop_iterate(_cl); 2458 } 2459 return false; 2460 } 2461 }; 2462 2463 // Iterates an ObjectClosure over all objects within a HeapRegion. 2464 2465 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2466 ObjectClosure* _cl; 2467 public: 2468 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2469 bool doHeapRegion(HeapRegion* r) { 2470 if (!r->is_continues_humongous()) { 2471 r->object_iterate(_cl); 2472 } 2473 return false; 2474 } 2475 }; 2476 2477 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2478 IterateObjectClosureRegionClosure blk(cl); 2479 heap_region_iterate(&blk); 2480 } 2481 2482 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2483 _hrm.iterate(cl); 2484 } 2485 2486 void 2487 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2488 uint worker_id, 2489 HeapRegionClaimer *hrclaimer, 2490 bool concurrent) const { 2491 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2492 } 2493 2494 // Clear the cached CSet starting regions and (more importantly) 2495 // the time stamps. Called when we reset the GC time stamp. 2496 void G1CollectedHeap::clear_cset_start_regions() { 2497 assert(_worker_cset_start_region != NULL, "sanity"); 2498 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2499 2500 int n_queues = MAX2((int)ParallelGCThreads, 1); 2501 for (int i = 0; i < n_queues; i++) { 2502 _worker_cset_start_region[i] = NULL; 2503 _worker_cset_start_region_time_stamp[i] = 0; 2504 } 2505 } 2506 2507 // Given the id of a worker, obtain or calculate a suitable 2508 // starting region for iterating over the current collection set. 2509 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2510 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2511 2512 HeapRegion* result = NULL; 2513 unsigned gc_time_stamp = get_gc_time_stamp(); 2514 2515 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2516 // Cached starting region for current worker was set 2517 // during the current pause - so it's valid. 2518 // Note: the cached starting heap region may be NULL 2519 // (when the collection set is empty). 2520 result = _worker_cset_start_region[worker_i]; 2521 assert(result == NULL || result->in_collection_set(), "sanity"); 2522 return result; 2523 } 2524 2525 // The cached entry was not valid so let's calculate 2526 // a suitable starting heap region for this worker. 2527 2528 // We want the parallel threads to start their collection 2529 // set iteration at different collection set regions to 2530 // avoid contention. 2531 // If we have: 2532 // n collection set regions 2533 // p threads 2534 // Then thread t will start at region floor ((t * n) / p) 2535 2536 result = g1_policy()->collection_set(); 2537 uint cs_size = g1_policy()->cset_region_length(); 2538 uint active_workers = workers()->active_workers(); 2539 assert(UseDynamicNumberOfGCThreads || 2540 active_workers == workers()->total_workers(), 2541 "Unless dynamic should use total workers"); 2542 2543 uint end_ind = (cs_size * worker_i) / active_workers; 2544 uint start_ind = 0; 2545 2546 if (worker_i > 0 && 2547 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2548 // Previous workers starting region is valid 2549 // so let's iterate from there 2550 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2551 result = _worker_cset_start_region[worker_i - 1]; 2552 } 2553 2554 for (uint i = start_ind; i < end_ind; i++) { 2555 result = result->next_in_collection_set(); 2556 } 2557 2558 // Note: the calculated starting heap region may be NULL 2559 // (when the collection set is empty). 2560 assert(result == NULL || result->in_collection_set(), "sanity"); 2561 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2562 "should be updated only once per pause"); 2563 _worker_cset_start_region[worker_i] = result; 2564 OrderAccess::storestore(); 2565 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2566 return result; 2567 } 2568 2569 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2570 HeapRegion* r = g1_policy()->collection_set(); 2571 while (r != NULL) { 2572 HeapRegion* next = r->next_in_collection_set(); 2573 if (cl->doHeapRegion(r)) { 2574 cl->incomplete(); 2575 return; 2576 } 2577 r = next; 2578 } 2579 } 2580 2581 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2582 HeapRegionClosure *cl) { 2583 if (r == NULL) { 2584 // The CSet is empty so there's nothing to do. 2585 return; 2586 } 2587 2588 assert(r->in_collection_set(), 2589 "Start region must be a member of the collection set."); 2590 HeapRegion* cur = r; 2591 while (cur != NULL) { 2592 HeapRegion* next = cur->next_in_collection_set(); 2593 if (cl->doHeapRegion(cur) && false) { 2594 cl->incomplete(); 2595 return; 2596 } 2597 cur = next; 2598 } 2599 cur = g1_policy()->collection_set(); 2600 while (cur != r) { 2601 HeapRegion* next = cur->next_in_collection_set(); 2602 if (cl->doHeapRegion(cur) && false) { 2603 cl->incomplete(); 2604 return; 2605 } 2606 cur = next; 2607 } 2608 } 2609 2610 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2611 HeapRegion* result = _hrm.next_region_in_heap(from); 2612 while (result != NULL && result->is_humongous()) { 2613 result = _hrm.next_region_in_heap(result); 2614 } 2615 return result; 2616 } 2617 2618 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2619 HeapRegion* hr = heap_region_containing(addr); 2620 return hr->block_start(addr); 2621 } 2622 2623 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2624 HeapRegion* hr = heap_region_containing(addr); 2625 return hr->block_size(addr); 2626 } 2627 2628 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2629 HeapRegion* hr = heap_region_containing(addr); 2630 return hr->block_is_obj(addr); 2631 } 2632 2633 bool G1CollectedHeap::supports_tlab_allocation() const { 2634 return true; 2635 } 2636 2637 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2638 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2639 } 2640 2641 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2642 return young_list()->eden_used_bytes(); 2643 } 2644 2645 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2646 // must be smaller than the humongous object limit. 2647 size_t G1CollectedHeap::max_tlab_size() const { 2648 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2649 } 2650 2651 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2652 // Return the remaining space in the cur alloc region, but not less than 2653 // the min TLAB size. 2654 2655 // Also, this value can be at most the humongous object threshold, 2656 // since we can't allow tlabs to grow big enough to accommodate 2657 // humongous objects. 2658 2659 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2660 size_t max_tlab = max_tlab_size() * wordSize; 2661 if (hr == NULL) { 2662 return max_tlab; 2663 } else { 2664 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2665 } 2666 } 2667 2668 size_t G1CollectedHeap::max_capacity() const { 2669 return _hrm.reserved().byte_size(); 2670 } 2671 2672 jlong G1CollectedHeap::millis_since_last_gc() { 2673 // assert(false, "NYI"); 2674 return 0; 2675 } 2676 2677 void G1CollectedHeap::prepare_for_verify() { 2678 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2679 ensure_parsability(false); 2680 } 2681 g1_rem_set()->prepare_for_verify(); 2682 } 2683 2684 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2685 VerifyOption vo) { 2686 switch (vo) { 2687 case VerifyOption_G1UsePrevMarking: 2688 return hr->obj_allocated_since_prev_marking(obj); 2689 case VerifyOption_G1UseNextMarking: 2690 return hr->obj_allocated_since_next_marking(obj); 2691 case VerifyOption_G1UseMarkWord: 2692 return false; 2693 default: 2694 ShouldNotReachHere(); 2695 } 2696 return false; // keep some compilers happy 2697 } 2698 2699 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2700 switch (vo) { 2701 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2702 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2703 case VerifyOption_G1UseMarkWord: return NULL; 2704 default: ShouldNotReachHere(); 2705 } 2706 return NULL; // keep some compilers happy 2707 } 2708 2709 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2710 switch (vo) { 2711 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2712 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2713 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2714 default: ShouldNotReachHere(); 2715 } 2716 return false; // keep some compilers happy 2717 } 2718 2719 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2720 switch (vo) { 2721 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2722 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2723 case VerifyOption_G1UseMarkWord: return "NONE"; 2724 default: ShouldNotReachHere(); 2725 } 2726 return NULL; // keep some compilers happy 2727 } 2728 2729 class VerifyRootsClosure: public OopClosure { 2730 private: 2731 G1CollectedHeap* _g1h; 2732 VerifyOption _vo; 2733 bool _failures; 2734 public: 2735 // _vo == UsePrevMarking -> use "prev" marking information, 2736 // _vo == UseNextMarking -> use "next" marking information, 2737 // _vo == UseMarkWord -> use mark word from object header. 2738 VerifyRootsClosure(VerifyOption vo) : 2739 _g1h(G1CollectedHeap::heap()), 2740 _vo(vo), 2741 _failures(false) { } 2742 2743 bool failures() { return _failures; } 2744 2745 template <class T> void do_oop_nv(T* p) { 2746 T heap_oop = oopDesc::load_heap_oop(p); 2747 if (!oopDesc::is_null(heap_oop)) { 2748 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2749 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2750 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2751 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj)); 2752 if (_vo == VerifyOption_G1UseMarkWord) { 2753 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark()); 2754 } 2755 obj->print_on(gclog_or_tty); 2756 _failures = true; 2757 } 2758 } 2759 } 2760 2761 void do_oop(oop* p) { do_oop_nv(p); } 2762 void do_oop(narrowOop* p) { do_oop_nv(p); } 2763 }; 2764 2765 class G1VerifyCodeRootOopClosure: public OopClosure { 2766 G1CollectedHeap* _g1h; 2767 OopClosure* _root_cl; 2768 nmethod* _nm; 2769 VerifyOption _vo; 2770 bool _failures; 2771 2772 template <class T> void do_oop_work(T* p) { 2773 // First verify that this root is live 2774 _root_cl->do_oop(p); 2775 2776 if (!G1VerifyHeapRegionCodeRoots) { 2777 // We're not verifying the code roots attached to heap region. 2778 return; 2779 } 2780 2781 // Don't check the code roots during marking verification in a full GC 2782 if (_vo == VerifyOption_G1UseMarkWord) { 2783 return; 2784 } 2785 2786 // Now verify that the current nmethod (which contains p) is 2787 // in the code root list of the heap region containing the 2788 // object referenced by p. 2789 2790 T heap_oop = oopDesc::load_heap_oop(p); 2791 if (!oopDesc::is_null(heap_oop)) { 2792 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2793 2794 // Now fetch the region containing the object 2795 HeapRegion* hr = _g1h->heap_region_containing(obj); 2796 HeapRegionRemSet* hrrs = hr->rem_set(); 2797 // Verify that the strong code root list for this region 2798 // contains the nmethod 2799 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2800 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2801 "from nmethod "PTR_FORMAT" not in strong " 2802 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2803 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2804 _failures = true; 2805 } 2806 } 2807 } 2808 2809 public: 2810 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2811 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2812 2813 void do_oop(oop* p) { do_oop_work(p); } 2814 void do_oop(narrowOop* p) { do_oop_work(p); } 2815 2816 void set_nmethod(nmethod* nm) { _nm = nm; } 2817 bool failures() { return _failures; } 2818 }; 2819 2820 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2821 G1VerifyCodeRootOopClosure* _oop_cl; 2822 2823 public: 2824 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2825 _oop_cl(oop_cl) {} 2826 2827 void do_code_blob(CodeBlob* cb) { 2828 nmethod* nm = cb->as_nmethod_or_null(); 2829 if (nm != NULL) { 2830 _oop_cl->set_nmethod(nm); 2831 nm->oops_do(_oop_cl); 2832 } 2833 } 2834 }; 2835 2836 class YoungRefCounterClosure : public OopClosure { 2837 G1CollectedHeap* _g1h; 2838 int _count; 2839 public: 2840 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2841 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2842 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2843 2844 int count() { return _count; } 2845 void reset_count() { _count = 0; }; 2846 }; 2847 2848 class VerifyKlassClosure: public KlassClosure { 2849 YoungRefCounterClosure _young_ref_counter_closure; 2850 OopClosure *_oop_closure; 2851 public: 2852 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2853 void do_klass(Klass* k) { 2854 k->oops_do(_oop_closure); 2855 2856 _young_ref_counter_closure.reset_count(); 2857 k->oops_do(&_young_ref_counter_closure); 2858 if (_young_ref_counter_closure.count() > 0) { 2859 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); 2860 } 2861 } 2862 }; 2863 2864 class VerifyLivenessOopClosure: public OopClosure { 2865 G1CollectedHeap* _g1h; 2866 VerifyOption _vo; 2867 public: 2868 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2869 _g1h(g1h), _vo(vo) 2870 { } 2871 void do_oop(narrowOop *p) { do_oop_work(p); } 2872 void do_oop( oop *p) { do_oop_work(p); } 2873 2874 template <class T> void do_oop_work(T *p) { 2875 oop obj = oopDesc::load_decode_heap_oop(p); 2876 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2877 "Dead object referenced by a not dead object"); 2878 } 2879 }; 2880 2881 class VerifyObjsInRegionClosure: public ObjectClosure { 2882 private: 2883 G1CollectedHeap* _g1h; 2884 size_t _live_bytes; 2885 HeapRegion *_hr; 2886 VerifyOption _vo; 2887 public: 2888 // _vo == UsePrevMarking -> use "prev" marking information, 2889 // _vo == UseNextMarking -> use "next" marking information, 2890 // _vo == UseMarkWord -> use mark word from object header. 2891 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2892 : _live_bytes(0), _hr(hr), _vo(vo) { 2893 _g1h = G1CollectedHeap::heap(); 2894 } 2895 void do_object(oop o) { 2896 VerifyLivenessOopClosure isLive(_g1h, _vo); 2897 assert(o != NULL, "Huh?"); 2898 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2899 // If the object is alive according to the mark word, 2900 // then verify that the marking information agrees. 2901 // Note we can't verify the contra-positive of the 2902 // above: if the object is dead (according to the mark 2903 // word), it may not be marked, or may have been marked 2904 // but has since became dead, or may have been allocated 2905 // since the last marking. 2906 if (_vo == VerifyOption_G1UseMarkWord) { 2907 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2908 } 2909 2910 o->oop_iterate_no_header(&isLive); 2911 if (!_hr->obj_allocated_since_prev_marking(o)) { 2912 size_t obj_size = o->size(); // Make sure we don't overflow 2913 _live_bytes += (obj_size * HeapWordSize); 2914 } 2915 } 2916 } 2917 size_t live_bytes() { return _live_bytes; } 2918 }; 2919 2920 class PrintObjsInRegionClosure : public ObjectClosure { 2921 HeapRegion *_hr; 2922 G1CollectedHeap *_g1; 2923 public: 2924 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2925 _g1 = G1CollectedHeap::heap(); 2926 }; 2927 2928 void do_object(oop o) { 2929 if (o != NULL) { 2930 HeapWord *start = (HeapWord *) o; 2931 size_t word_sz = o->size(); 2932 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2933 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2934 p2i(o), word_sz, 2935 _g1->isMarkedPrev(o), 2936 _g1->isMarkedNext(o), 2937 _hr->obj_allocated_since_prev_marking(o)); 2938 HeapWord *end = start + word_sz; 2939 HeapWord *cur; 2940 int *val; 2941 for (cur = start; cur < end; cur++) { 2942 val = (int *) cur; 2943 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", p2i(val), *val); 2944 } 2945 } 2946 } 2947 }; 2948 2949 class VerifyRegionClosure: public HeapRegionClosure { 2950 private: 2951 bool _par; 2952 VerifyOption _vo; 2953 bool _failures; 2954 public: 2955 // _vo == UsePrevMarking -> use "prev" marking information, 2956 // _vo == UseNextMarking -> use "next" marking information, 2957 // _vo == UseMarkWord -> use mark word from object header. 2958 VerifyRegionClosure(bool par, VerifyOption vo) 2959 : _par(par), 2960 _vo(vo), 2961 _failures(false) {} 2962 2963 bool failures() { 2964 return _failures; 2965 } 2966 2967 bool doHeapRegion(HeapRegion* r) { 2968 if (!r->is_continues_humongous()) { 2969 bool failures = false; 2970 r->verify(_vo, &failures); 2971 if (failures) { 2972 _failures = true; 2973 } else { 2974 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2975 r->object_iterate(¬_dead_yet_cl); 2976 if (_vo != VerifyOption_G1UseNextMarking) { 2977 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2978 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2979 "max_live_bytes "SIZE_FORMAT" " 2980 "< calculated "SIZE_FORMAT, 2981 p2i(r->bottom()), p2i(r->end()), 2982 r->max_live_bytes(), 2983 not_dead_yet_cl.live_bytes()); 2984 _failures = true; 2985 } 2986 } else { 2987 // When vo == UseNextMarking we cannot currently do a sanity 2988 // check on the live bytes as the calculation has not been 2989 // finalized yet. 2990 } 2991 } 2992 } 2993 return false; // stop the region iteration if we hit a failure 2994 } 2995 }; 2996 2997 // This is the task used for parallel verification of the heap regions 2998 2999 class G1ParVerifyTask: public AbstractGangTask { 3000 private: 3001 G1CollectedHeap* _g1h; 3002 VerifyOption _vo; 3003 bool _failures; 3004 HeapRegionClaimer _hrclaimer; 3005 3006 public: 3007 // _vo == UsePrevMarking -> use "prev" marking information, 3008 // _vo == UseNextMarking -> use "next" marking information, 3009 // _vo == UseMarkWord -> use mark word from object header. 3010 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3011 AbstractGangTask("Parallel verify task"), 3012 _g1h(g1h), 3013 _vo(vo), 3014 _failures(false), 3015 _hrclaimer(g1h->workers()->active_workers()) {} 3016 3017 bool failures() { 3018 return _failures; 3019 } 3020 3021 void work(uint worker_id) { 3022 HandleMark hm; 3023 VerifyRegionClosure blk(true, _vo); 3024 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3025 if (blk.failures()) { 3026 _failures = true; 3027 } 3028 } 3029 }; 3030 3031 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3032 if (SafepointSynchronize::is_at_safepoint()) { 3033 assert(Thread::current()->is_VM_thread(), 3034 "Expected to be executed serially by the VM thread at this point"); 3035 3036 if (!silent) { gclog_or_tty->print("Roots "); } 3037 VerifyRootsClosure rootsCl(vo); 3038 VerifyKlassClosure klassCl(this, &rootsCl); 3039 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3040 3041 // We apply the relevant closures to all the oops in the 3042 // system dictionary, class loader data graph, the string table 3043 // and the nmethods in the code cache. 3044 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3045 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3046 3047 { 3048 G1RootProcessor root_processor(this); 3049 root_processor.process_all_roots(&rootsCl, 3050 &cldCl, 3051 &blobsCl); 3052 } 3053 3054 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3055 3056 if (vo != VerifyOption_G1UseMarkWord) { 3057 // If we're verifying during a full GC then the region sets 3058 // will have been torn down at the start of the GC. Therefore 3059 // verifying the region sets will fail. So we only verify 3060 // the region sets when not in a full GC. 3061 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3062 verify_region_sets(); 3063 } 3064 3065 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3066 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3067 3068 G1ParVerifyTask task(this, vo); 3069 assert(UseDynamicNumberOfGCThreads || 3070 workers()->active_workers() == workers()->total_workers(), 3071 "If not dynamic should be using all the workers"); 3072 int n_workers = workers()->active_workers(); 3073 set_par_threads(n_workers); 3074 workers()->run_task(&task); 3075 set_par_threads(0); 3076 if (task.failures()) { 3077 failures = true; 3078 } 3079 3080 } else { 3081 VerifyRegionClosure blk(false, vo); 3082 heap_region_iterate(&blk); 3083 if (blk.failures()) { 3084 failures = true; 3085 } 3086 } 3087 3088 if (G1StringDedup::is_enabled()) { 3089 if (!silent) gclog_or_tty->print("StrDedup "); 3090 G1StringDedup::verify(); 3091 } 3092 3093 if (failures) { 3094 gclog_or_tty->print_cr("Heap:"); 3095 // It helps to have the per-region information in the output to 3096 // help us track down what went wrong. This is why we call 3097 // print_extended_on() instead of print_on(). 3098 print_extended_on(gclog_or_tty); 3099 gclog_or_tty->cr(); 3100 gclog_or_tty->flush(); 3101 } 3102 guarantee(!failures, "there should not have been any failures"); 3103 } else { 3104 if (!silent) { 3105 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3106 if (G1StringDedup::is_enabled()) { 3107 gclog_or_tty->print(", StrDedup"); 3108 } 3109 gclog_or_tty->print(") "); 3110 } 3111 } 3112 } 3113 3114 void G1CollectedHeap::verify(bool silent) { 3115 verify(silent, VerifyOption_G1UsePrevMarking); 3116 } 3117 3118 double G1CollectedHeap::verify(bool guard, const char* msg) { 3119 double verify_time_ms = 0.0; 3120 3121 if (guard && total_collections() >= VerifyGCStartAt) { 3122 double verify_start = os::elapsedTime(); 3123 HandleMark hm; // Discard invalid handles created during verification 3124 prepare_for_verify(); 3125 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3126 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3127 } 3128 3129 return verify_time_ms; 3130 } 3131 3132 void G1CollectedHeap::verify_before_gc() { 3133 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3134 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3135 } 3136 3137 void G1CollectedHeap::verify_after_gc() { 3138 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3139 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3140 } 3141 3142 class PrintRegionClosure: public HeapRegionClosure { 3143 outputStream* _st; 3144 public: 3145 PrintRegionClosure(outputStream* st) : _st(st) {} 3146 bool doHeapRegion(HeapRegion* r) { 3147 r->print_on(_st); 3148 return false; 3149 } 3150 }; 3151 3152 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3153 const HeapRegion* hr, 3154 const VerifyOption vo) const { 3155 switch (vo) { 3156 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3157 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3158 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3159 default: ShouldNotReachHere(); 3160 } 3161 return false; // keep some compilers happy 3162 } 3163 3164 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3165 const VerifyOption vo) const { 3166 switch (vo) { 3167 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3168 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3169 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3170 default: ShouldNotReachHere(); 3171 } 3172 return false; // keep some compilers happy 3173 } 3174 3175 void G1CollectedHeap::print_on(outputStream* st) const { 3176 st->print(" %-20s", "garbage-first heap"); 3177 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3178 capacity()/K, used_unlocked()/K); 3179 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3180 p2i(_hrm.reserved().start()), 3181 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3182 p2i(_hrm.reserved().end())); 3183 st->cr(); 3184 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3185 uint young_regions = _young_list->length(); 3186 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3187 (size_t) young_regions * HeapRegion::GrainBytes / K); 3188 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3189 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3190 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3191 st->cr(); 3192 MetaspaceAux::print_on(st); 3193 } 3194 3195 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3196 print_on(st); 3197 3198 // Print the per-region information. 3199 st->cr(); 3200 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3201 "HS=humongous(starts), HC=humongous(continues), " 3202 "CS=collection set, F=free, TS=gc time stamp, " 3203 "PTAMS=previous top-at-mark-start, " 3204 "NTAMS=next top-at-mark-start)"); 3205 PrintRegionClosure blk(st); 3206 heap_region_iterate(&blk); 3207 } 3208 3209 void G1CollectedHeap::print_on_error(outputStream* st) const { 3210 this->CollectedHeap::print_on_error(st); 3211 3212 if (_cm != NULL) { 3213 st->cr(); 3214 _cm->print_on_error(st); 3215 } 3216 } 3217 3218 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3219 workers()->print_worker_threads_on(st); 3220 _cmThread->print_on(st); 3221 st->cr(); 3222 _cm->print_worker_threads_on(st); 3223 _cg1r->print_worker_threads_on(st); 3224 if (G1StringDedup::is_enabled()) { 3225 G1StringDedup::print_worker_threads_on(st); 3226 } 3227 } 3228 3229 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3230 workers()->threads_do(tc); 3231 tc->do_thread(_cmThread); 3232 _cg1r->threads_do(tc); 3233 if (G1StringDedup::is_enabled()) { 3234 G1StringDedup::threads_do(tc); 3235 } 3236 } 3237 3238 void G1CollectedHeap::print_tracing_info() const { 3239 // We'll overload this to mean "trace GC pause statistics." 3240 if (TraceYoungGenTime || TraceOldGenTime) { 3241 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3242 // to that. 3243 g1_policy()->print_tracing_info(); 3244 } 3245 if (G1SummarizeRSetStats) { 3246 g1_rem_set()->print_summary_info(); 3247 } 3248 if (G1SummarizeConcMark) { 3249 concurrent_mark()->print_summary_info(); 3250 } 3251 g1_policy()->print_yg_surv_rate_info(); 3252 } 3253 3254 #ifndef PRODUCT 3255 // Helpful for debugging RSet issues. 3256 3257 class PrintRSetsClosure : public HeapRegionClosure { 3258 private: 3259 const char* _msg; 3260 size_t _occupied_sum; 3261 3262 public: 3263 bool doHeapRegion(HeapRegion* r) { 3264 HeapRegionRemSet* hrrs = r->rem_set(); 3265 size_t occupied = hrrs->occupied(); 3266 _occupied_sum += occupied; 3267 3268 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3269 HR_FORMAT_PARAMS(r)); 3270 if (occupied == 0) { 3271 gclog_or_tty->print_cr(" RSet is empty"); 3272 } else { 3273 hrrs->print(); 3274 } 3275 gclog_or_tty->print_cr("----------"); 3276 return false; 3277 } 3278 3279 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3280 gclog_or_tty->cr(); 3281 gclog_or_tty->print_cr("========================================"); 3282 gclog_or_tty->print_cr("%s", msg); 3283 gclog_or_tty->cr(); 3284 } 3285 3286 ~PrintRSetsClosure() { 3287 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3288 gclog_or_tty->print_cr("========================================"); 3289 gclog_or_tty->cr(); 3290 } 3291 }; 3292 3293 void G1CollectedHeap::print_cset_rsets() { 3294 PrintRSetsClosure cl("Printing CSet RSets"); 3295 collection_set_iterate(&cl); 3296 } 3297 3298 void G1CollectedHeap::print_all_rsets() { 3299 PrintRSetsClosure cl("Printing All RSets");; 3300 heap_region_iterate(&cl); 3301 } 3302 #endif // PRODUCT 3303 3304 G1CollectedHeap* G1CollectedHeap::heap() { 3305 CollectedHeap* heap = Universe::heap(); 3306 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3307 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3308 return (G1CollectedHeap*)heap; 3309 } 3310 3311 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3312 // always_do_update_barrier = false; 3313 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3314 // Fill TLAB's and such 3315 accumulate_statistics_all_tlabs(); 3316 ensure_parsability(true); 3317 3318 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3319 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3320 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3321 } 3322 } 3323 3324 void G1CollectedHeap::gc_epilogue(bool full) { 3325 3326 if (G1SummarizeRSetStats && 3327 (G1SummarizeRSetStatsPeriod > 0) && 3328 // we are at the end of the GC. Total collections has already been increased. 3329 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3330 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3331 } 3332 3333 // FIXME: what is this about? 3334 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3335 // is set. 3336 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3337 "derived pointer present")); 3338 // always_do_update_barrier = true; 3339 3340 resize_all_tlabs(); 3341 allocation_context_stats().update(full); 3342 3343 // We have just completed a GC. Update the soft reference 3344 // policy with the new heap occupancy 3345 Universe::update_heap_info_at_gc(); 3346 } 3347 3348 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3349 uint gc_count_before, 3350 bool* succeeded, 3351 GCCause::Cause gc_cause) { 3352 assert_heap_not_locked_and_not_at_safepoint(); 3353 g1_policy()->record_stop_world_start(); 3354 VM_G1IncCollectionPause op(gc_count_before, 3355 word_size, 3356 false, /* should_initiate_conc_mark */ 3357 g1_policy()->max_pause_time_ms(), 3358 gc_cause); 3359 3360 op.set_allocation_context(AllocationContext::current()); 3361 VMThread::execute(&op); 3362 3363 HeapWord* result = op.result(); 3364 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3365 assert(result == NULL || ret_succeeded, 3366 "the result should be NULL if the VM did not succeed"); 3367 *succeeded = ret_succeeded; 3368 3369 assert_heap_not_locked(); 3370 return result; 3371 } 3372 3373 void 3374 G1CollectedHeap::doConcurrentMark() { 3375 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3376 if (!_cmThread->in_progress()) { 3377 _cmThread->set_started(); 3378 CGC_lock->notify(); 3379 } 3380 } 3381 3382 size_t G1CollectedHeap::pending_card_num() { 3383 size_t extra_cards = 0; 3384 JavaThread *curr = Threads::first(); 3385 while (curr != NULL) { 3386 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3387 extra_cards += dcq.size(); 3388 curr = curr->next(); 3389 } 3390 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3391 size_t buffer_size = dcqs.buffer_size(); 3392 size_t buffer_num = dcqs.completed_buffers_num(); 3393 3394 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3395 // in bytes - not the number of 'entries'. We need to convert 3396 // into a number of cards. 3397 return (buffer_size * buffer_num + extra_cards) / oopSize; 3398 } 3399 3400 size_t G1CollectedHeap::cards_scanned() { 3401 return g1_rem_set()->cardsScanned(); 3402 } 3403 3404 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3405 private: 3406 size_t _total_humongous; 3407 size_t _candidate_humongous; 3408 3409 DirtyCardQueue _dcq; 3410 3411 // We don't nominate objects with many remembered set entries, on 3412 // the assumption that such objects are likely still live. 3413 bool is_remset_small(HeapRegion* region) const { 3414 HeapRegionRemSet* const rset = region->rem_set(); 3415 return G1EagerReclaimHumongousObjectsWithStaleRefs 3416 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3417 : rset->is_empty(); 3418 } 3419 3420 bool is_typeArray_region(HeapRegion* region) const { 3421 return oop(region->bottom())->is_typeArray(); 3422 } 3423 3424 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3425 assert(region->is_starts_humongous(), "Must start a humongous object"); 3426 3427 // Candidate selection must satisfy the following constraints 3428 // while concurrent marking is in progress: 3429 // 3430 // * In order to maintain SATB invariants, an object must not be 3431 // reclaimed if it was allocated before the start of marking and 3432 // has not had its references scanned. Such an object must have 3433 // its references (including type metadata) scanned to ensure no 3434 // live objects are missed by the marking process. Objects 3435 // allocated after the start of concurrent marking don't need to 3436 // be scanned. 3437 // 3438 // * An object must not be reclaimed if it is on the concurrent 3439 // mark stack. Objects allocated after the start of concurrent 3440 // marking are never pushed on the mark stack. 3441 // 3442 // Nominating only objects allocated after the start of concurrent 3443 // marking is sufficient to meet both constraints. This may miss 3444 // some objects that satisfy the constraints, but the marking data 3445 // structures don't support efficiently performing the needed 3446 // additional tests or scrubbing of the mark stack. 3447 // 3448 // However, we presently only nominate is_typeArray() objects. 3449 // A humongous object containing references induces remembered 3450 // set entries on other regions. In order to reclaim such an 3451 // object, those remembered sets would need to be cleaned up. 3452 // 3453 // We also treat is_typeArray() objects specially, allowing them 3454 // to be reclaimed even if allocated before the start of 3455 // concurrent mark. For this we rely on mark stack insertion to 3456 // exclude is_typeArray() objects, preventing reclaiming an object 3457 // that is in the mark stack. We also rely on the metadata for 3458 // such objects to be built-in and so ensured to be kept live. 3459 // Frequent allocation and drop of large binary blobs is an 3460 // important use case for eager reclaim, and this special handling 3461 // may reduce needed headroom. 3462 3463 return is_typeArray_region(region) && is_remset_small(region); 3464 } 3465 3466 public: 3467 RegisterHumongousWithInCSetFastTestClosure() 3468 : _total_humongous(0), 3469 _candidate_humongous(0), 3470 _dcq(&JavaThread::dirty_card_queue_set()) { 3471 } 3472 3473 virtual bool doHeapRegion(HeapRegion* r) { 3474 if (!r->is_starts_humongous()) { 3475 return false; 3476 } 3477 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3478 3479 bool is_candidate = humongous_region_is_candidate(g1h, r); 3480 uint rindex = r->hrm_index(); 3481 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3482 if (is_candidate) { 3483 _candidate_humongous++; 3484 g1h->register_humongous_region_with_cset(rindex); 3485 // Is_candidate already filters out humongous object with large remembered sets. 3486 // If we have a humongous object with a few remembered sets, we simply flush these 3487 // remembered set entries into the DCQS. That will result in automatic 3488 // re-evaluation of their remembered set entries during the following evacuation 3489 // phase. 3490 if (!r->rem_set()->is_empty()) { 3491 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3492 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3493 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3494 HeapRegionRemSetIterator hrrs(r->rem_set()); 3495 size_t card_index; 3496 while (hrrs.has_next(card_index)) { 3497 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3498 // The remembered set might contain references to already freed 3499 // regions. Filter out such entries to avoid failing card table 3500 // verification. 3501 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3502 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3503 *card_ptr = CardTableModRefBS::dirty_card_val(); 3504 _dcq.enqueue(card_ptr); 3505 } 3506 } 3507 } 3508 r->rem_set()->clear_locked(); 3509 } 3510 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3511 } 3512 _total_humongous++; 3513 3514 return false; 3515 } 3516 3517 size_t total_humongous() const { return _total_humongous; } 3518 size_t candidate_humongous() const { return _candidate_humongous; } 3519 3520 void flush_rem_set_entries() { _dcq.flush(); } 3521 }; 3522 3523 void G1CollectedHeap::register_humongous_regions_with_cset() { 3524 if (!G1EagerReclaimHumongousObjects) { 3525 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3526 return; 3527 } 3528 double time = os::elapsed_counter(); 3529 3530 // Collect reclaim candidate information and register candidates with cset. 3531 RegisterHumongousWithInCSetFastTestClosure cl; 3532 heap_region_iterate(&cl); 3533 3534 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3535 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3536 cl.total_humongous(), 3537 cl.candidate_humongous()); 3538 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3539 3540 // Finally flush all remembered set entries to re-check into the global DCQS. 3541 cl.flush_rem_set_entries(); 3542 } 3543 3544 void 3545 G1CollectedHeap::setup_surviving_young_words() { 3546 assert(_surviving_young_words == NULL, "pre-condition"); 3547 uint array_length = g1_policy()->young_cset_region_length(); 3548 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3549 if (_surviving_young_words == NULL) { 3550 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3551 "Not enough space for young surv words summary."); 3552 } 3553 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3554 #ifdef ASSERT 3555 for (uint i = 0; i < array_length; ++i) { 3556 assert( _surviving_young_words[i] == 0, "memset above" ); 3557 } 3558 #endif // !ASSERT 3559 } 3560 3561 void 3562 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3563 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3564 uint array_length = g1_policy()->young_cset_region_length(); 3565 for (uint i = 0; i < array_length; ++i) { 3566 _surviving_young_words[i] += surv_young_words[i]; 3567 } 3568 } 3569 3570 void 3571 G1CollectedHeap::cleanup_surviving_young_words() { 3572 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3573 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3574 _surviving_young_words = NULL; 3575 } 3576 3577 #ifdef ASSERT 3578 class VerifyCSetClosure: public HeapRegionClosure { 3579 public: 3580 bool doHeapRegion(HeapRegion* hr) { 3581 // Here we check that the CSet region's RSet is ready for parallel 3582 // iteration. The fields that we'll verify are only manipulated 3583 // when the region is part of a CSet and is collected. Afterwards, 3584 // we reset these fields when we clear the region's RSet (when the 3585 // region is freed) so they are ready when the region is 3586 // re-allocated. The only exception to this is if there's an 3587 // evacuation failure and instead of freeing the region we leave 3588 // it in the heap. In that case, we reset these fields during 3589 // evacuation failure handling. 3590 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3591 3592 // Here's a good place to add any other checks we'd like to 3593 // perform on CSet regions. 3594 return false; 3595 } 3596 }; 3597 #endif // ASSERT 3598 3599 #if TASKQUEUE_STATS 3600 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3601 st->print_raw_cr("GC Task Stats"); 3602 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3603 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3604 } 3605 3606 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3607 print_taskqueue_stats_hdr(st); 3608 3609 TaskQueueStats totals; 3610 const int n = workers()->total_workers(); 3611 for (int i = 0; i < n; ++i) { 3612 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3613 totals += task_queue(i)->stats; 3614 } 3615 st->print_raw("tot "); totals.print(st); st->cr(); 3616 3617 DEBUG_ONLY(totals.verify()); 3618 } 3619 3620 void G1CollectedHeap::reset_taskqueue_stats() { 3621 const int n = workers()->total_workers(); 3622 for (int i = 0; i < n; ++i) { 3623 task_queue(i)->stats.reset(); 3624 } 3625 } 3626 #endif // TASKQUEUE_STATS 3627 3628 void G1CollectedHeap::log_gc_header() { 3629 if (!G1Log::fine()) { 3630 return; 3631 } 3632 3633 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3634 3635 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3636 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3637 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3638 3639 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3640 } 3641 3642 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3643 if (!G1Log::fine()) { 3644 return; 3645 } 3646 3647 if (G1Log::finer()) { 3648 if (evacuation_failed()) { 3649 gclog_or_tty->print(" (to-space exhausted)"); 3650 } 3651 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3652 g1_policy()->phase_times()->note_gc_end(); 3653 g1_policy()->phase_times()->print(pause_time_sec); 3654 g1_policy()->print_detailed_heap_transition(); 3655 } else { 3656 if (evacuation_failed()) { 3657 gclog_or_tty->print("--"); 3658 } 3659 g1_policy()->print_heap_transition(); 3660 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3661 } 3662 gclog_or_tty->flush(); 3663 } 3664 3665 bool 3666 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3667 assert_at_safepoint(true /* should_be_vm_thread */); 3668 guarantee(!is_gc_active(), "collection is not reentrant"); 3669 3670 if (GC_locker::check_active_before_gc()) { 3671 return false; 3672 } 3673 3674 _gc_timer_stw->register_gc_start(); 3675 3676 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3677 3678 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3679 ResourceMark rm; 3680 3681 print_heap_before_gc(); 3682 trace_heap_before_gc(_gc_tracer_stw); 3683 3684 verify_region_sets_optional(); 3685 verify_dirty_young_regions(); 3686 3687 // This call will decide whether this pause is an initial-mark 3688 // pause. If it is, during_initial_mark_pause() will return true 3689 // for the duration of this pause. 3690 g1_policy()->decide_on_conc_mark_initiation(); 3691 3692 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3693 assert(!g1_policy()->during_initial_mark_pause() || 3694 g1_policy()->gcs_are_young(), "sanity"); 3695 3696 // We also do not allow mixed GCs during marking. 3697 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3698 3699 // Record whether this pause is an initial mark. When the current 3700 // thread has completed its logging output and it's safe to signal 3701 // the CM thread, the flag's value in the policy has been reset. 3702 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3703 3704 // Inner scope for scope based logging, timers, and stats collection 3705 { 3706 EvacuationInfo evacuation_info; 3707 3708 if (g1_policy()->during_initial_mark_pause()) { 3709 // We are about to start a marking cycle, so we increment the 3710 // full collection counter. 3711 increment_old_marking_cycles_started(); 3712 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3713 } 3714 3715 _gc_tracer_stw->report_yc_type(yc_type()); 3716 3717 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3718 3719 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3720 workers()->active_workers(), 3721 Threads::number_of_non_daemon_threads()); 3722 assert(UseDynamicNumberOfGCThreads || 3723 active_workers == workers()->total_workers(), 3724 "If not dynamic should be using all the workers"); 3725 workers()->set_active_workers(active_workers); 3726 3727 double pause_start_sec = os::elapsedTime(); 3728 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3729 log_gc_header(); 3730 3731 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3732 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3733 3734 // If the secondary_free_list is not empty, append it to the 3735 // free_list. No need to wait for the cleanup operation to finish; 3736 // the region allocation code will check the secondary_free_list 3737 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3738 // set, skip this step so that the region allocation code has to 3739 // get entries from the secondary_free_list. 3740 if (!G1StressConcRegionFreeing) { 3741 append_secondary_free_list_if_not_empty_with_lock(); 3742 } 3743 3744 assert(check_young_list_well_formed(), "young list should be well formed"); 3745 3746 // Don't dynamically change the number of GC threads this early. A value of 3747 // 0 is used to indicate serial work. When parallel work is done, 3748 // it will be set. 3749 3750 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3751 IsGCActiveMark x; 3752 3753 gc_prologue(false); 3754 increment_total_collections(false /* full gc */); 3755 increment_gc_time_stamp(); 3756 3757 verify_before_gc(); 3758 3759 check_bitmaps("GC Start"); 3760 3761 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3762 3763 // Please see comment in g1CollectedHeap.hpp and 3764 // G1CollectedHeap::ref_processing_init() to see how 3765 // reference processing currently works in G1. 3766 3767 // Enable discovery in the STW reference processor 3768 ref_processor_stw()->enable_discovery(); 3769 3770 { 3771 // We want to temporarily turn off discovery by the 3772 // CM ref processor, if necessary, and turn it back on 3773 // on again later if we do. Using a scoped 3774 // NoRefDiscovery object will do this. 3775 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3776 3777 // Forget the current alloc region (we might even choose it to be part 3778 // of the collection set!). 3779 _allocator->release_mutator_alloc_region(); 3780 3781 // We should call this after we retire the mutator alloc 3782 // region(s) so that all the ALLOC / RETIRE events are generated 3783 // before the start GC event. 3784 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3785 3786 // This timing is only used by the ergonomics to handle our pause target. 3787 // It is unclear why this should not include the full pause. We will 3788 // investigate this in CR 7178365. 3789 // 3790 // Preserving the old comment here if that helps the investigation: 3791 // 3792 // The elapsed time induced by the start time below deliberately elides 3793 // the possible verification above. 3794 double sample_start_time_sec = os::elapsedTime(); 3795 3796 #if YOUNG_LIST_VERBOSE 3797 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3798 _young_list->print(); 3799 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3800 #endif // YOUNG_LIST_VERBOSE 3801 3802 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3803 3804 double scan_wait_start = os::elapsedTime(); 3805 // We have to wait until the CM threads finish scanning the 3806 // root regions as it's the only way to ensure that all the 3807 // objects on them have been correctly scanned before we start 3808 // moving them during the GC. 3809 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3810 double wait_time_ms = 0.0; 3811 if (waited) { 3812 double scan_wait_end = os::elapsedTime(); 3813 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3814 } 3815 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3816 3817 #if YOUNG_LIST_VERBOSE 3818 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3819 _young_list->print(); 3820 #endif // YOUNG_LIST_VERBOSE 3821 3822 if (g1_policy()->during_initial_mark_pause()) { 3823 concurrent_mark()->checkpointRootsInitialPre(); 3824 } 3825 3826 #if YOUNG_LIST_VERBOSE 3827 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3828 _young_list->print(); 3829 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3830 #endif // YOUNG_LIST_VERBOSE 3831 3832 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3833 3834 register_humongous_regions_with_cset(); 3835 3836 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3837 3838 _cm->note_start_of_gc(); 3839 // We should not verify the per-thread SATB buffers given that 3840 // we have not filtered them yet (we'll do so during the 3841 // GC). We also call this after finalize_cset() to 3842 // ensure that the CSet has been finalized. 3843 _cm->verify_no_cset_oops(true /* verify_stacks */, 3844 true /* verify_enqueued_buffers */, 3845 false /* verify_thread_buffers */, 3846 true /* verify_fingers */); 3847 3848 if (_hr_printer.is_active()) { 3849 HeapRegion* hr = g1_policy()->collection_set(); 3850 while (hr != NULL) { 3851 _hr_printer.cset(hr); 3852 hr = hr->next_in_collection_set(); 3853 } 3854 } 3855 3856 #ifdef ASSERT 3857 VerifyCSetClosure cl; 3858 collection_set_iterate(&cl); 3859 #endif // ASSERT 3860 3861 setup_surviving_young_words(); 3862 3863 // Initialize the GC alloc regions. 3864 _allocator->init_gc_alloc_regions(evacuation_info); 3865 3866 // Actually do the work... 3867 evacuate_collection_set(evacuation_info); 3868 3869 // We do this to mainly verify the per-thread SATB buffers 3870 // (which have been filtered by now) since we didn't verify 3871 // them earlier. No point in re-checking the stacks / enqueued 3872 // buffers given that the CSet has not changed since last time 3873 // we checked. 3874 _cm->verify_no_cset_oops(false /* verify_stacks */, 3875 false /* verify_enqueued_buffers */, 3876 true /* verify_thread_buffers */, 3877 true /* verify_fingers */); 3878 3879 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3880 3881 eagerly_reclaim_humongous_regions(); 3882 3883 g1_policy()->clear_collection_set(); 3884 3885 cleanup_surviving_young_words(); 3886 3887 // Start a new incremental collection set for the next pause. 3888 g1_policy()->start_incremental_cset_building(); 3889 3890 clear_cset_fast_test(); 3891 3892 _young_list->reset_sampled_info(); 3893 3894 // Don't check the whole heap at this point as the 3895 // GC alloc regions from this pause have been tagged 3896 // as survivors and moved on to the survivor list. 3897 // Survivor regions will fail the !is_young() check. 3898 assert(check_young_list_empty(false /* check_heap */), 3899 "young list should be empty"); 3900 3901 #if YOUNG_LIST_VERBOSE 3902 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3903 _young_list->print(); 3904 #endif // YOUNG_LIST_VERBOSE 3905 3906 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3907 _young_list->first_survivor_region(), 3908 _young_list->last_survivor_region()); 3909 3910 _young_list->reset_auxilary_lists(); 3911 3912 if (evacuation_failed()) { 3913 _allocator->set_used(recalculate_used()); 3914 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3915 for (uint i = 0; i < n_queues; i++) { 3916 if (_evacuation_failed_info_array[i].has_failed()) { 3917 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3918 } 3919 } 3920 } else { 3921 // The "used" of the the collection set have already been subtracted 3922 // when they were freed. Add in the bytes evacuated. 3923 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3924 } 3925 3926 if (g1_policy()->during_initial_mark_pause()) { 3927 // We have to do this before we notify the CM threads that 3928 // they can start working to make sure that all the 3929 // appropriate initialization is done on the CM object. 3930 concurrent_mark()->checkpointRootsInitialPost(); 3931 set_marking_started(); 3932 // Note that we don't actually trigger the CM thread at 3933 // this point. We do that later when we're sure that 3934 // the current thread has completed its logging output. 3935 } 3936 3937 allocate_dummy_regions(); 3938 3939 #if YOUNG_LIST_VERBOSE 3940 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3941 _young_list->print(); 3942 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3943 #endif // YOUNG_LIST_VERBOSE 3944 3945 _allocator->init_mutator_alloc_region(); 3946 3947 { 3948 size_t expand_bytes = g1_policy()->expansion_amount(); 3949 if (expand_bytes > 0) { 3950 size_t bytes_before = capacity(); 3951 // No need for an ergo verbose message here, 3952 // expansion_amount() does this when it returns a value > 0. 3953 if (!expand(expand_bytes)) { 3954 // We failed to expand the heap. Cannot do anything about it. 3955 } 3956 } 3957 } 3958 3959 // We redo the verification but now wrt to the new CSet which 3960 // has just got initialized after the previous CSet was freed. 3961 _cm->verify_no_cset_oops(true /* verify_stacks */, 3962 true /* verify_enqueued_buffers */, 3963 true /* verify_thread_buffers */, 3964 true /* verify_fingers */); 3965 _cm->note_end_of_gc(); 3966 3967 // This timing is only used by the ergonomics to handle our pause target. 3968 // It is unclear why this should not include the full pause. We will 3969 // investigate this in CR 7178365. 3970 double sample_end_time_sec = os::elapsedTime(); 3971 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3972 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3973 3974 MemoryService::track_memory_usage(); 3975 3976 // In prepare_for_verify() below we'll need to scan the deferred 3977 // update buffers to bring the RSets up-to-date if 3978 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3979 // the update buffers we'll probably need to scan cards on the 3980 // regions we just allocated to (i.e., the GC alloc 3981 // regions). However, during the last GC we called 3982 // set_saved_mark() on all the GC alloc regions, so card 3983 // scanning might skip the [saved_mark_word()...top()] area of 3984 // those regions (i.e., the area we allocated objects into 3985 // during the last GC). But it shouldn't. Given that 3986 // saved_mark_word() is conditional on whether the GC time stamp 3987 // on the region is current or not, by incrementing the GC time 3988 // stamp here we invalidate all the GC time stamps on all the 3989 // regions and saved_mark_word() will simply return top() for 3990 // all the regions. This is a nicer way of ensuring this rather 3991 // than iterating over the regions and fixing them. In fact, the 3992 // GC time stamp increment here also ensures that 3993 // saved_mark_word() will return top() between pauses, i.e., 3994 // during concurrent refinement. So we don't need the 3995 // is_gc_active() check to decided which top to use when 3996 // scanning cards (see CR 7039627). 3997 increment_gc_time_stamp(); 3998 3999 verify_after_gc(); 4000 check_bitmaps("GC End"); 4001 4002 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4003 ref_processor_stw()->verify_no_references_recorded(); 4004 4005 // CM reference discovery will be re-enabled if necessary. 4006 } 4007 4008 // We should do this after we potentially expand the heap so 4009 // that all the COMMIT events are generated before the end GC 4010 // event, and after we retire the GC alloc regions so that all 4011 // RETIRE events are generated before the end GC event. 4012 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4013 4014 #ifdef TRACESPINNING 4015 ParallelTaskTerminator::print_termination_counts(); 4016 #endif 4017 4018 gc_epilogue(false); 4019 } 4020 4021 // Print the remainder of the GC log output. 4022 log_gc_footer(os::elapsedTime() - pause_start_sec); 4023 4024 // It is not yet to safe to tell the concurrent mark to 4025 // start as we have some optional output below. We don't want the 4026 // output from the concurrent mark thread interfering with this 4027 // logging output either. 4028 4029 _hrm.verify_optional(); 4030 verify_region_sets_optional(); 4031 4032 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4033 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4034 4035 print_heap_after_gc(); 4036 trace_heap_after_gc(_gc_tracer_stw); 4037 4038 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4039 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4040 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4041 // before any GC notifications are raised. 4042 g1mm()->update_sizes(); 4043 4044 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4045 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4046 _gc_timer_stw->register_gc_end(); 4047 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4048 } 4049 // It should now be safe to tell the concurrent mark thread to start 4050 // without its logging output interfering with the logging output 4051 // that came from the pause. 4052 4053 if (should_start_conc_mark) { 4054 // CAUTION: after the doConcurrentMark() call below, 4055 // the concurrent marking thread(s) could be running 4056 // concurrently with us. Make sure that anything after 4057 // this point does not assume that we are the only GC thread 4058 // running. Note: of course, the actual marking work will 4059 // not start until the safepoint itself is released in 4060 // SuspendibleThreadSet::desynchronize(). 4061 doConcurrentMark(); 4062 } 4063 4064 return true; 4065 } 4066 4067 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4068 _drain_in_progress = false; 4069 set_evac_failure_closure(cl); 4070 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4071 } 4072 4073 void G1CollectedHeap::finalize_for_evac_failure() { 4074 assert(_evac_failure_scan_stack != NULL && 4075 _evac_failure_scan_stack->length() == 0, 4076 "Postcondition"); 4077 assert(!_drain_in_progress, "Postcondition"); 4078 delete _evac_failure_scan_stack; 4079 _evac_failure_scan_stack = NULL; 4080 } 4081 4082 void G1CollectedHeap::remove_self_forwarding_pointers() { 4083 double remove_self_forwards_start = os::elapsedTime(); 4084 4085 set_par_threads(); 4086 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4087 workers()->run_task(&rsfp_task); 4088 set_par_threads(0); 4089 4090 // Now restore saved marks, if any. 4091 assert(_objs_with_preserved_marks.size() == 4092 _preserved_marks_of_objs.size(), "Both or none."); 4093 while (!_objs_with_preserved_marks.is_empty()) { 4094 oop obj = _objs_with_preserved_marks.pop(); 4095 markOop m = _preserved_marks_of_objs.pop(); 4096 obj->set_mark(m); 4097 } 4098 _objs_with_preserved_marks.clear(true); 4099 _preserved_marks_of_objs.clear(true); 4100 4101 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4102 } 4103 4104 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4105 _evac_failure_scan_stack->push(obj); 4106 } 4107 4108 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4109 assert(_evac_failure_scan_stack != NULL, "precondition"); 4110 4111 while (_evac_failure_scan_stack->length() > 0) { 4112 oop obj = _evac_failure_scan_stack->pop(); 4113 _evac_failure_closure->set_region(heap_region_containing(obj)); 4114 obj->oop_iterate_backwards(_evac_failure_closure); 4115 } 4116 } 4117 4118 oop 4119 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4120 oop old) { 4121 assert(obj_in_cs(old), 4122 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4123 p2i(old))); 4124 markOop m = old->mark(); 4125 oop forward_ptr = old->forward_to_atomic(old); 4126 if (forward_ptr == NULL) { 4127 // Forward-to-self succeeded. 4128 assert(_par_scan_state != NULL, "par scan state"); 4129 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4130 uint queue_num = _par_scan_state->queue_num(); 4131 4132 _evacuation_failed = true; 4133 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4134 if (_evac_failure_closure != cl) { 4135 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4136 assert(!_drain_in_progress, 4137 "Should only be true while someone holds the lock."); 4138 // Set the global evac-failure closure to the current thread's. 4139 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4140 set_evac_failure_closure(cl); 4141 // Now do the common part. 4142 handle_evacuation_failure_common(old, m); 4143 // Reset to NULL. 4144 set_evac_failure_closure(NULL); 4145 } else { 4146 // The lock is already held, and this is recursive. 4147 assert(_drain_in_progress, "This should only be the recursive case."); 4148 handle_evacuation_failure_common(old, m); 4149 } 4150 return old; 4151 } else { 4152 // Forward-to-self failed. Either someone else managed to allocate 4153 // space for this object (old != forward_ptr) or they beat us in 4154 // self-forwarding it (old == forward_ptr). 4155 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4156 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4157 "should not be in the CSet", 4158 p2i(old), p2i(forward_ptr))); 4159 return forward_ptr; 4160 } 4161 } 4162 4163 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4164 preserve_mark_if_necessary(old, m); 4165 4166 HeapRegion* r = heap_region_containing(old); 4167 if (!r->evacuation_failed()) { 4168 r->set_evacuation_failed(true); 4169 _hr_printer.evac_failure(r); 4170 } 4171 4172 push_on_evac_failure_scan_stack(old); 4173 4174 if (!_drain_in_progress) { 4175 // prevent recursion in copy_to_survivor_space() 4176 _drain_in_progress = true; 4177 drain_evac_failure_scan_stack(); 4178 _drain_in_progress = false; 4179 } 4180 } 4181 4182 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4183 assert(evacuation_failed(), "Oversaving!"); 4184 // We want to call the "for_promotion_failure" version only in the 4185 // case of a promotion failure. 4186 if (m->must_be_preserved_for_promotion_failure(obj)) { 4187 _objs_with_preserved_marks.push(obj); 4188 _preserved_marks_of_objs.push(m); 4189 } 4190 } 4191 4192 void G1ParCopyHelper::mark_object(oop obj) { 4193 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4194 4195 // We know that the object is not moving so it's safe to read its size. 4196 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4197 } 4198 4199 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4200 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4201 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4202 assert(from_obj != to_obj, "should not be self-forwarded"); 4203 4204 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4205 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4206 4207 // The object might be in the process of being copied by another 4208 // worker so we cannot trust that its to-space image is 4209 // well-formed. So we have to read its size from its from-space 4210 // image which we know should not be changing. 4211 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4212 } 4213 4214 template <class T> 4215 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4216 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4217 _scanned_klass->record_modified_oops(); 4218 } 4219 } 4220 4221 template <G1Barrier barrier, G1Mark do_mark_object> 4222 template <class T> 4223 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4224 T heap_oop = oopDesc::load_heap_oop(p); 4225 4226 if (oopDesc::is_null(heap_oop)) { 4227 return; 4228 } 4229 4230 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4231 4232 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4233 4234 const InCSetState state = _g1->in_cset_state(obj); 4235 if (state.is_in_cset()) { 4236 oop forwardee; 4237 markOop m = obj->mark(); 4238 if (m->is_marked()) { 4239 forwardee = (oop) m->decode_pointer(); 4240 } else { 4241 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4242 } 4243 assert(forwardee != NULL, "forwardee should not be NULL"); 4244 oopDesc::encode_store_heap_oop(p, forwardee); 4245 if (do_mark_object != G1MarkNone && forwardee != obj) { 4246 // If the object is self-forwarded we don't need to explicitly 4247 // mark it, the evacuation failure protocol will do so. 4248 mark_forwarded_object(obj, forwardee); 4249 } 4250 4251 if (barrier == G1BarrierKlass) { 4252 do_klass_barrier(p, forwardee); 4253 } 4254 } else { 4255 if (state.is_humongous()) { 4256 _g1->set_humongous_is_live(obj); 4257 } 4258 // The object is not in collection set. If we're a root scanning 4259 // closure during an initial mark pause then attempt to mark the object. 4260 if (do_mark_object == G1MarkFromRoot) { 4261 mark_object(obj); 4262 } 4263 } 4264 4265 if (barrier == G1BarrierEvac) { 4266 _par_scan_state->update_rs(_from, p, _worker_id); 4267 } 4268 } 4269 4270 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4271 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4272 4273 class G1ParEvacuateFollowersClosure : public VoidClosure { 4274 protected: 4275 G1CollectedHeap* _g1h; 4276 G1ParScanThreadState* _par_scan_state; 4277 RefToScanQueueSet* _queues; 4278 ParallelTaskTerminator* _terminator; 4279 4280 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4281 RefToScanQueueSet* queues() { return _queues; } 4282 ParallelTaskTerminator* terminator() { return _terminator; } 4283 4284 public: 4285 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4286 G1ParScanThreadState* par_scan_state, 4287 RefToScanQueueSet* queues, 4288 ParallelTaskTerminator* terminator) 4289 : _g1h(g1h), _par_scan_state(par_scan_state), 4290 _queues(queues), _terminator(terminator) {} 4291 4292 void do_void(); 4293 4294 private: 4295 inline bool offer_termination(); 4296 }; 4297 4298 bool G1ParEvacuateFollowersClosure::offer_termination() { 4299 G1ParScanThreadState* const pss = par_scan_state(); 4300 pss->start_term_time(); 4301 const bool res = terminator()->offer_termination(); 4302 pss->end_term_time(); 4303 return res; 4304 } 4305 4306 void G1ParEvacuateFollowersClosure::do_void() { 4307 G1ParScanThreadState* const pss = par_scan_state(); 4308 pss->trim_queue(); 4309 do { 4310 pss->steal_and_trim_queue(queues()); 4311 } while (!offer_termination()); 4312 } 4313 4314 class G1KlassScanClosure : public KlassClosure { 4315 G1ParCopyHelper* _closure; 4316 bool _process_only_dirty; 4317 int _count; 4318 public: 4319 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4320 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4321 void do_klass(Klass* klass) { 4322 // If the klass has not been dirtied we know that there's 4323 // no references into the young gen and we can skip it. 4324 if (!_process_only_dirty || klass->has_modified_oops()) { 4325 // Clean the klass since we're going to scavenge all the metadata. 4326 klass->clear_modified_oops(); 4327 4328 // Tell the closure that this klass is the Klass to scavenge 4329 // and is the one to dirty if oops are left pointing into the young gen. 4330 _closure->set_scanned_klass(klass); 4331 4332 klass->oops_do(_closure); 4333 4334 _closure->set_scanned_klass(NULL); 4335 } 4336 _count++; 4337 } 4338 }; 4339 4340 class G1ParTask : public AbstractGangTask { 4341 protected: 4342 G1CollectedHeap* _g1h; 4343 RefToScanQueueSet *_queues; 4344 G1RootProcessor* _root_processor; 4345 ParallelTaskTerminator _terminator; 4346 uint _n_workers; 4347 4348 Mutex _stats_lock; 4349 Mutex* stats_lock() { return &_stats_lock; } 4350 4351 public: 4352 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4353 : AbstractGangTask("G1 collection"), 4354 _g1h(g1h), 4355 _queues(task_queues), 4356 _root_processor(root_processor), 4357 _terminator(0, _queues), 4358 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4359 {} 4360 4361 RefToScanQueueSet* queues() { return _queues; } 4362 4363 RefToScanQueue *work_queue(int i) { 4364 return queues()->queue(i); 4365 } 4366 4367 ParallelTaskTerminator* terminator() { return &_terminator; } 4368 4369 virtual void set_for_termination(int active_workers) { 4370 _root_processor->set_num_workers(active_workers); 4371 terminator()->reset_for_reuse(active_workers); 4372 _n_workers = active_workers; 4373 } 4374 4375 // Helps out with CLD processing. 4376 // 4377 // During InitialMark we need to: 4378 // 1) Scavenge all CLDs for the young GC. 4379 // 2) Mark all objects directly reachable from strong CLDs. 4380 template <G1Mark do_mark_object> 4381 class G1CLDClosure : public CLDClosure { 4382 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4383 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4384 G1KlassScanClosure _klass_in_cld_closure; 4385 bool _claim; 4386 4387 public: 4388 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4389 bool only_young, bool claim) 4390 : _oop_closure(oop_closure), 4391 _oop_in_klass_closure(oop_closure->g1(), 4392 oop_closure->pss(), 4393 oop_closure->rp()), 4394 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4395 _claim(claim) { 4396 4397 } 4398 4399 void do_cld(ClassLoaderData* cld) { 4400 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4401 } 4402 }; 4403 4404 void work(uint worker_id) { 4405 if (worker_id >= _n_workers) return; // no work needed this round 4406 4407 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4408 4409 { 4410 ResourceMark rm; 4411 HandleMark hm; 4412 4413 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4414 4415 G1ParScanThreadState pss(_g1h, worker_id, rp); 4416 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4417 4418 pss.set_evac_failure_closure(&evac_failure_cl); 4419 4420 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4421 4422 // Non-IM young GC. 4423 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4424 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4425 only_young, // Only process dirty klasses. 4426 false); // No need to claim CLDs. 4427 // IM young GC. 4428 // Strong roots closures. 4429 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4430 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4431 false, // Process all klasses. 4432 true); // Need to claim CLDs. 4433 // Weak roots closures. 4434 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4435 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4436 false, // Process all klasses. 4437 true); // Need to claim CLDs. 4438 4439 OopClosure* strong_root_cl; 4440 OopClosure* weak_root_cl; 4441 CLDClosure* strong_cld_cl; 4442 CLDClosure* weak_cld_cl; 4443 4444 bool trace_metadata = false; 4445 4446 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4447 // We also need to mark copied objects. 4448 strong_root_cl = &scan_mark_root_cl; 4449 strong_cld_cl = &scan_mark_cld_cl; 4450 if (ClassUnloadingWithConcurrentMark) { 4451 weak_root_cl = &scan_mark_weak_root_cl; 4452 weak_cld_cl = &scan_mark_weak_cld_cl; 4453 trace_metadata = true; 4454 } else { 4455 weak_root_cl = &scan_mark_root_cl; 4456 weak_cld_cl = &scan_mark_cld_cl; 4457 } 4458 } else { 4459 strong_root_cl = &scan_only_root_cl; 4460 weak_root_cl = &scan_only_root_cl; 4461 strong_cld_cl = &scan_only_cld_cl; 4462 weak_cld_cl = &scan_only_cld_cl; 4463 } 4464 4465 pss.start_strong_roots(); 4466 4467 _root_processor->evacuate_roots(strong_root_cl, 4468 weak_root_cl, 4469 strong_cld_cl, 4470 weak_cld_cl, 4471 trace_metadata, 4472 worker_id); 4473 4474 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4475 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4476 weak_root_cl, 4477 worker_id); 4478 pss.end_strong_roots(); 4479 4480 { 4481 double start = os::elapsedTime(); 4482 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4483 evac.do_void(); 4484 double elapsed_sec = os::elapsedTime() - start; 4485 double term_sec = pss.term_time(); 4486 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4487 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4488 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4489 } 4490 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4491 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4492 4493 if (PrintTerminationStats) { 4494 MutexLocker x(stats_lock()); 4495 pss.print_termination_stats(worker_id); 4496 } 4497 4498 assert(pss.queue_is_empty(), "should be empty"); 4499 4500 // Close the inner scope so that the ResourceMark and HandleMark 4501 // destructors are executed here and are included as part of the 4502 // "GC Worker Time". 4503 } 4504 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4505 } 4506 }; 4507 4508 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4509 private: 4510 BoolObjectClosure* _is_alive; 4511 int _initial_string_table_size; 4512 int _initial_symbol_table_size; 4513 4514 bool _process_strings; 4515 int _strings_processed; 4516 int _strings_removed; 4517 4518 bool _process_symbols; 4519 int _symbols_processed; 4520 int _symbols_removed; 4521 4522 public: 4523 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4524 AbstractGangTask("String/Symbol Unlinking"), 4525 _is_alive(is_alive), 4526 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4527 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4528 4529 _initial_string_table_size = StringTable::the_table()->table_size(); 4530 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4531 if (process_strings) { 4532 StringTable::clear_parallel_claimed_index(); 4533 } 4534 if (process_symbols) { 4535 SymbolTable::clear_parallel_claimed_index(); 4536 } 4537 } 4538 4539 ~G1StringSymbolTableUnlinkTask() { 4540 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4541 err_msg("claim value %d after unlink less than initial string table size %d", 4542 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4543 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4544 err_msg("claim value %d after unlink less than initial symbol table size %d", 4545 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4546 4547 if (G1TraceStringSymbolTableScrubbing) { 4548 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4549 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4550 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4551 strings_processed(), strings_removed(), 4552 symbols_processed(), symbols_removed()); 4553 } 4554 } 4555 4556 void work(uint worker_id) { 4557 int strings_processed = 0; 4558 int strings_removed = 0; 4559 int symbols_processed = 0; 4560 int symbols_removed = 0; 4561 if (_process_strings) { 4562 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4563 Atomic::add(strings_processed, &_strings_processed); 4564 Atomic::add(strings_removed, &_strings_removed); 4565 } 4566 if (_process_symbols) { 4567 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4568 Atomic::add(symbols_processed, &_symbols_processed); 4569 Atomic::add(symbols_removed, &_symbols_removed); 4570 } 4571 } 4572 4573 size_t strings_processed() const { return (size_t)_strings_processed; } 4574 size_t strings_removed() const { return (size_t)_strings_removed; } 4575 4576 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4577 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4578 }; 4579 4580 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4581 private: 4582 static Monitor* _lock; 4583 4584 BoolObjectClosure* const _is_alive; 4585 const bool _unloading_occurred; 4586 const uint _num_workers; 4587 4588 // Variables used to claim nmethods. 4589 nmethod* _first_nmethod; 4590 volatile nmethod* _claimed_nmethod; 4591 4592 // The list of nmethods that need to be processed by the second pass. 4593 volatile nmethod* _postponed_list; 4594 volatile uint _num_entered_barrier; 4595 4596 public: 4597 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4598 _is_alive(is_alive), 4599 _unloading_occurred(unloading_occurred), 4600 _num_workers(num_workers), 4601 _first_nmethod(NULL), 4602 _claimed_nmethod(NULL), 4603 _postponed_list(NULL), 4604 _num_entered_barrier(0) 4605 { 4606 nmethod::increase_unloading_clock(); 4607 // Get first alive nmethod 4608 NMethodIterator iter = NMethodIterator(); 4609 if(iter.next_alive()) { 4610 _first_nmethod = iter.method(); 4611 } 4612 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4613 } 4614 4615 ~G1CodeCacheUnloadingTask() { 4616 CodeCache::verify_clean_inline_caches(); 4617 4618 CodeCache::set_needs_cache_clean(false); 4619 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4620 4621 CodeCache::verify_icholder_relocations(); 4622 } 4623 4624 private: 4625 void add_to_postponed_list(nmethod* nm) { 4626 nmethod* old; 4627 do { 4628 old = (nmethod*)_postponed_list; 4629 nm->set_unloading_next(old); 4630 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4631 } 4632 4633 void clean_nmethod(nmethod* nm) { 4634 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4635 4636 if (postponed) { 4637 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4638 add_to_postponed_list(nm); 4639 } 4640 4641 // Mark that this thread has been cleaned/unloaded. 4642 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4643 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4644 } 4645 4646 void clean_nmethod_postponed(nmethod* nm) { 4647 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4648 } 4649 4650 static const int MaxClaimNmethods = 16; 4651 4652 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4653 nmethod* first; 4654 NMethodIterator last; 4655 4656 do { 4657 *num_claimed_nmethods = 0; 4658 4659 first = (nmethod*)_claimed_nmethod; 4660 last = NMethodIterator(first); 4661 4662 if (first != NULL) { 4663 4664 for (int i = 0; i < MaxClaimNmethods; i++) { 4665 if (!last.next_alive()) { 4666 break; 4667 } 4668 claimed_nmethods[i] = last.method(); 4669 (*num_claimed_nmethods)++; 4670 } 4671 } 4672 4673 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4674 } 4675 4676 nmethod* claim_postponed_nmethod() { 4677 nmethod* claim; 4678 nmethod* next; 4679 4680 do { 4681 claim = (nmethod*)_postponed_list; 4682 if (claim == NULL) { 4683 return NULL; 4684 } 4685 4686 next = claim->unloading_next(); 4687 4688 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4689 4690 return claim; 4691 } 4692 4693 public: 4694 // Mark that we're done with the first pass of nmethod cleaning. 4695 void barrier_mark(uint worker_id) { 4696 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4697 _num_entered_barrier++; 4698 if (_num_entered_barrier == _num_workers) { 4699 ml.notify_all(); 4700 } 4701 } 4702 4703 // See if we have to wait for the other workers to 4704 // finish their first-pass nmethod cleaning work. 4705 void barrier_wait(uint worker_id) { 4706 if (_num_entered_barrier < _num_workers) { 4707 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4708 while (_num_entered_barrier < _num_workers) { 4709 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4710 } 4711 } 4712 } 4713 4714 // Cleaning and unloading of nmethods. Some work has to be postponed 4715 // to the second pass, when we know which nmethods survive. 4716 void work_first_pass(uint worker_id) { 4717 // The first nmethods is claimed by the first worker. 4718 if (worker_id == 0 && _first_nmethod != NULL) { 4719 clean_nmethod(_first_nmethod); 4720 _first_nmethod = NULL; 4721 } 4722 4723 int num_claimed_nmethods; 4724 nmethod* claimed_nmethods[MaxClaimNmethods]; 4725 4726 while (true) { 4727 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4728 4729 if (num_claimed_nmethods == 0) { 4730 break; 4731 } 4732 4733 for (int i = 0; i < num_claimed_nmethods; i++) { 4734 clean_nmethod(claimed_nmethods[i]); 4735 } 4736 } 4737 } 4738 4739 void work_second_pass(uint worker_id) { 4740 nmethod* nm; 4741 // Take care of postponed nmethods. 4742 while ((nm = claim_postponed_nmethod()) != NULL) { 4743 clean_nmethod_postponed(nm); 4744 } 4745 } 4746 }; 4747 4748 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4749 4750 class G1KlassCleaningTask : public StackObj { 4751 BoolObjectClosure* _is_alive; 4752 volatile jint _clean_klass_tree_claimed; 4753 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4754 4755 public: 4756 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4757 _is_alive(is_alive), 4758 _clean_klass_tree_claimed(0), 4759 _klass_iterator() { 4760 } 4761 4762 private: 4763 bool claim_clean_klass_tree_task() { 4764 if (_clean_klass_tree_claimed) { 4765 return false; 4766 } 4767 4768 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4769 } 4770 4771 InstanceKlass* claim_next_klass() { 4772 Klass* klass; 4773 do { 4774 klass =_klass_iterator.next_klass(); 4775 } while (klass != NULL && !klass->oop_is_instance()); 4776 4777 return (InstanceKlass*)klass; 4778 } 4779 4780 public: 4781 4782 void clean_klass(InstanceKlass* ik) { 4783 ik->clean_implementors_list(_is_alive); 4784 ik->clean_method_data(_is_alive); 4785 4786 // G1 specific cleanup work that has 4787 // been moved here to be done in parallel. 4788 ik->clean_dependent_nmethods(); 4789 } 4790 4791 void work() { 4792 ResourceMark rm; 4793 4794 // One worker will clean the subklass/sibling klass tree. 4795 if (claim_clean_klass_tree_task()) { 4796 Klass::clean_subklass_tree(_is_alive); 4797 } 4798 4799 // All workers will help cleaning the classes, 4800 InstanceKlass* klass; 4801 while ((klass = claim_next_klass()) != NULL) { 4802 clean_klass(klass); 4803 } 4804 } 4805 }; 4806 4807 // To minimize the remark pause times, the tasks below are done in parallel. 4808 class G1ParallelCleaningTask : public AbstractGangTask { 4809 private: 4810 G1StringSymbolTableUnlinkTask _string_symbol_task; 4811 G1CodeCacheUnloadingTask _code_cache_task; 4812 G1KlassCleaningTask _klass_cleaning_task; 4813 4814 public: 4815 // The constructor is run in the VMThread. 4816 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4817 AbstractGangTask("Parallel Cleaning"), 4818 _string_symbol_task(is_alive, process_strings, process_symbols), 4819 _code_cache_task(num_workers, is_alive, unloading_occurred), 4820 _klass_cleaning_task(is_alive) { 4821 } 4822 4823 // The parallel work done by all worker threads. 4824 void work(uint worker_id) { 4825 // Do first pass of code cache cleaning. 4826 _code_cache_task.work_first_pass(worker_id); 4827 4828 // Let the threads mark that the first pass is done. 4829 _code_cache_task.barrier_mark(worker_id); 4830 4831 // Clean the Strings and Symbols. 4832 _string_symbol_task.work(worker_id); 4833 4834 // Wait for all workers to finish the first code cache cleaning pass. 4835 _code_cache_task.barrier_wait(worker_id); 4836 4837 // Do the second code cache cleaning work, which realize on 4838 // the liveness information gathered during the first pass. 4839 _code_cache_task.work_second_pass(worker_id); 4840 4841 // Clean all klasses that were not unloaded. 4842 _klass_cleaning_task.work(); 4843 } 4844 }; 4845 4846 4847 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4848 bool process_strings, 4849 bool process_symbols, 4850 bool class_unloading_occurred) { 4851 uint n_workers = workers()->active_workers(); 4852 4853 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4854 n_workers, class_unloading_occurred); 4855 set_par_threads(n_workers); 4856 workers()->run_task(&g1_unlink_task); 4857 set_par_threads(0); 4858 } 4859 4860 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4861 bool process_strings, bool process_symbols) { 4862 { 4863 uint n_workers = workers()->active_workers(); 4864 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4865 set_par_threads(n_workers); 4866 workers()->run_task(&g1_unlink_task); 4867 set_par_threads(0); 4868 } 4869 4870 if (G1StringDedup::is_enabled()) { 4871 G1StringDedup::unlink(is_alive); 4872 } 4873 } 4874 4875 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4876 private: 4877 DirtyCardQueueSet* _queue; 4878 public: 4879 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4880 4881 virtual void work(uint worker_id) { 4882 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4883 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4884 4885 RedirtyLoggedCardTableEntryClosure cl; 4886 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4887 4888 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4889 } 4890 }; 4891 4892 void G1CollectedHeap::redirty_logged_cards() { 4893 double redirty_logged_cards_start = os::elapsedTime(); 4894 4895 uint n_workers = workers()->active_workers(); 4896 4897 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4898 dirty_card_queue_set().reset_for_par_iteration(); 4899 set_par_threads(n_workers); 4900 workers()->run_task(&redirty_task); 4901 set_par_threads(0); 4902 4903 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4904 dcq.merge_bufferlists(&dirty_card_queue_set()); 4905 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4906 4907 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4908 } 4909 4910 // Weak Reference Processing support 4911 4912 // An always "is_alive" closure that is used to preserve referents. 4913 // If the object is non-null then it's alive. Used in the preservation 4914 // of referent objects that are pointed to by reference objects 4915 // discovered by the CM ref processor. 4916 class G1AlwaysAliveClosure: public BoolObjectClosure { 4917 G1CollectedHeap* _g1; 4918 public: 4919 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4920 bool do_object_b(oop p) { 4921 if (p != NULL) { 4922 return true; 4923 } 4924 return false; 4925 } 4926 }; 4927 4928 bool G1STWIsAliveClosure::do_object_b(oop p) { 4929 // An object is reachable if it is outside the collection set, 4930 // or is inside and copied. 4931 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4932 } 4933 4934 // Non Copying Keep Alive closure 4935 class G1KeepAliveClosure: public OopClosure { 4936 G1CollectedHeap* _g1; 4937 public: 4938 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4939 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4940 void do_oop(oop* p) { 4941 oop obj = *p; 4942 assert(obj != NULL, "the caller should have filtered out NULL values"); 4943 4944 const InCSetState cset_state = _g1->in_cset_state(obj); 4945 if (!cset_state.is_in_cset_or_humongous()) { 4946 return; 4947 } 4948 if (cset_state.is_in_cset()) { 4949 assert( obj->is_forwarded(), "invariant" ); 4950 *p = obj->forwardee(); 4951 } else { 4952 assert(!obj->is_forwarded(), "invariant" ); 4953 assert(cset_state.is_humongous(), 4954 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4955 _g1->set_humongous_is_live(obj); 4956 } 4957 } 4958 }; 4959 4960 // Copying Keep Alive closure - can be called from both 4961 // serial and parallel code as long as different worker 4962 // threads utilize different G1ParScanThreadState instances 4963 // and different queues. 4964 4965 class G1CopyingKeepAliveClosure: public OopClosure { 4966 G1CollectedHeap* _g1h; 4967 OopClosure* _copy_non_heap_obj_cl; 4968 G1ParScanThreadState* _par_scan_state; 4969 4970 public: 4971 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4972 OopClosure* non_heap_obj_cl, 4973 G1ParScanThreadState* pss): 4974 _g1h(g1h), 4975 _copy_non_heap_obj_cl(non_heap_obj_cl), 4976 _par_scan_state(pss) 4977 {} 4978 4979 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4980 virtual void do_oop( oop* p) { do_oop_work(p); } 4981 4982 template <class T> void do_oop_work(T* p) { 4983 oop obj = oopDesc::load_decode_heap_oop(p); 4984 4985 if (_g1h->is_in_cset_or_humongous(obj)) { 4986 // If the referent object has been forwarded (either copied 4987 // to a new location or to itself in the event of an 4988 // evacuation failure) then we need to update the reference 4989 // field and, if both reference and referent are in the G1 4990 // heap, update the RSet for the referent. 4991 // 4992 // If the referent has not been forwarded then we have to keep 4993 // it alive by policy. Therefore we have copy the referent. 4994 // 4995 // If the reference field is in the G1 heap then we can push 4996 // on the PSS queue. When the queue is drained (after each 4997 // phase of reference processing) the object and it's followers 4998 // will be copied, the reference field set to point to the 4999 // new location, and the RSet updated. Otherwise we need to 5000 // use the the non-heap or metadata closures directly to copy 5001 // the referent object and update the pointer, while avoiding 5002 // updating the RSet. 5003 5004 if (_g1h->is_in_g1_reserved(p)) { 5005 _par_scan_state->push_on_queue(p); 5006 } else { 5007 assert(!Metaspace::contains((const void*)p), 5008 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 5009 _copy_non_heap_obj_cl->do_oop(p); 5010 } 5011 } 5012 } 5013 }; 5014 5015 // Serial drain queue closure. Called as the 'complete_gc' 5016 // closure for each discovered list in some of the 5017 // reference processing phases. 5018 5019 class G1STWDrainQueueClosure: public VoidClosure { 5020 protected: 5021 G1CollectedHeap* _g1h; 5022 G1ParScanThreadState* _par_scan_state; 5023 5024 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5025 5026 public: 5027 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5028 _g1h(g1h), 5029 _par_scan_state(pss) 5030 { } 5031 5032 void do_void() { 5033 G1ParScanThreadState* const pss = par_scan_state(); 5034 pss->trim_queue(); 5035 } 5036 }; 5037 5038 // Parallel Reference Processing closures 5039 5040 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5041 // processing during G1 evacuation pauses. 5042 5043 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5044 private: 5045 G1CollectedHeap* _g1h; 5046 RefToScanQueueSet* _queues; 5047 FlexibleWorkGang* _workers; 5048 int _active_workers; 5049 5050 public: 5051 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5052 FlexibleWorkGang* workers, 5053 RefToScanQueueSet *task_queues, 5054 int n_workers) : 5055 _g1h(g1h), 5056 _queues(task_queues), 5057 _workers(workers), 5058 _active_workers(n_workers) 5059 { 5060 assert(n_workers > 0, "shouldn't call this otherwise"); 5061 } 5062 5063 // Executes the given task using concurrent marking worker threads. 5064 virtual void execute(ProcessTask& task); 5065 virtual void execute(EnqueueTask& task); 5066 }; 5067 5068 // Gang task for possibly parallel reference processing 5069 5070 class G1STWRefProcTaskProxy: public AbstractGangTask { 5071 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5072 ProcessTask& _proc_task; 5073 G1CollectedHeap* _g1h; 5074 RefToScanQueueSet *_task_queues; 5075 ParallelTaskTerminator* _terminator; 5076 5077 public: 5078 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5079 G1CollectedHeap* g1h, 5080 RefToScanQueueSet *task_queues, 5081 ParallelTaskTerminator* terminator) : 5082 AbstractGangTask("Process reference objects in parallel"), 5083 _proc_task(proc_task), 5084 _g1h(g1h), 5085 _task_queues(task_queues), 5086 _terminator(terminator) 5087 {} 5088 5089 virtual void work(uint worker_id) { 5090 // The reference processing task executed by a single worker. 5091 ResourceMark rm; 5092 HandleMark hm; 5093 5094 G1STWIsAliveClosure is_alive(_g1h); 5095 5096 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5097 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5098 5099 pss.set_evac_failure_closure(&evac_failure_cl); 5100 5101 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5102 5103 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5104 5105 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5106 5107 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5108 // We also need to mark copied objects. 5109 copy_non_heap_cl = ©_mark_non_heap_cl; 5110 } 5111 5112 // Keep alive closure. 5113 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5114 5115 // Complete GC closure 5116 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5117 5118 // Call the reference processing task's work routine. 5119 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5120 5121 // Note we cannot assert that the refs array is empty here as not all 5122 // of the processing tasks (specifically phase2 - pp2_work) execute 5123 // the complete_gc closure (which ordinarily would drain the queue) so 5124 // the queue may not be empty. 5125 } 5126 }; 5127 5128 // Driver routine for parallel reference processing. 5129 // Creates an instance of the ref processing gang 5130 // task and has the worker threads execute it. 5131 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5132 assert(_workers != NULL, "Need parallel worker threads."); 5133 5134 ParallelTaskTerminator terminator(_active_workers, _queues); 5135 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5136 5137 _g1h->set_par_threads(_active_workers); 5138 _workers->run_task(&proc_task_proxy); 5139 _g1h->set_par_threads(0); 5140 } 5141 5142 // Gang task for parallel reference enqueueing. 5143 5144 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5145 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5146 EnqueueTask& _enq_task; 5147 5148 public: 5149 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5150 AbstractGangTask("Enqueue reference objects in parallel"), 5151 _enq_task(enq_task) 5152 { } 5153 5154 virtual void work(uint worker_id) { 5155 _enq_task.work(worker_id); 5156 } 5157 }; 5158 5159 // Driver routine for parallel reference enqueueing. 5160 // Creates an instance of the ref enqueueing gang 5161 // task and has the worker threads execute it. 5162 5163 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5164 assert(_workers != NULL, "Need parallel worker threads."); 5165 5166 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5167 5168 _g1h->set_par_threads(_active_workers); 5169 _workers->run_task(&enq_task_proxy); 5170 _g1h->set_par_threads(0); 5171 } 5172 5173 // End of weak reference support closures 5174 5175 // Abstract task used to preserve (i.e. copy) any referent objects 5176 // that are in the collection set and are pointed to by reference 5177 // objects discovered by the CM ref processor. 5178 5179 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5180 protected: 5181 G1CollectedHeap* _g1h; 5182 RefToScanQueueSet *_queues; 5183 ParallelTaskTerminator _terminator; 5184 uint _n_workers; 5185 5186 public: 5187 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5188 AbstractGangTask("ParPreserveCMReferents"), 5189 _g1h(g1h), 5190 _queues(task_queues), 5191 _terminator(workers, _queues), 5192 _n_workers(workers) 5193 { } 5194 5195 void work(uint worker_id) { 5196 ResourceMark rm; 5197 HandleMark hm; 5198 5199 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5200 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5201 5202 pss.set_evac_failure_closure(&evac_failure_cl); 5203 5204 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5205 5206 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5207 5208 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5209 5210 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5211 5212 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5213 // We also need to mark copied objects. 5214 copy_non_heap_cl = ©_mark_non_heap_cl; 5215 } 5216 5217 // Is alive closure 5218 G1AlwaysAliveClosure always_alive(_g1h); 5219 5220 // Copying keep alive closure. Applied to referent objects that need 5221 // to be copied. 5222 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5223 5224 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5225 5226 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5227 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5228 5229 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5230 // So this must be true - but assert just in case someone decides to 5231 // change the worker ids. 5232 assert(worker_id < limit, "sanity"); 5233 assert(!rp->discovery_is_atomic(), "check this code"); 5234 5235 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5236 for (uint idx = worker_id; idx < limit; idx += stride) { 5237 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5238 5239 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5240 while (iter.has_next()) { 5241 // Since discovery is not atomic for the CM ref processor, we 5242 // can see some null referent objects. 5243 iter.load_ptrs(DEBUG_ONLY(true)); 5244 oop ref = iter.obj(); 5245 5246 // This will filter nulls. 5247 if (iter.is_referent_alive()) { 5248 iter.make_referent_alive(); 5249 } 5250 iter.move_to_next(); 5251 } 5252 } 5253 5254 // Drain the queue - which may cause stealing 5255 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5256 drain_queue.do_void(); 5257 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5258 assert(pss.queue_is_empty(), "should be"); 5259 } 5260 }; 5261 5262 // Weak Reference processing during an evacuation pause (part 1). 5263 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5264 double ref_proc_start = os::elapsedTime(); 5265 5266 ReferenceProcessor* rp = _ref_processor_stw; 5267 assert(rp->discovery_enabled(), "should have been enabled"); 5268 5269 // Any reference objects, in the collection set, that were 'discovered' 5270 // by the CM ref processor should have already been copied (either by 5271 // applying the external root copy closure to the discovered lists, or 5272 // by following an RSet entry). 5273 // 5274 // But some of the referents, that are in the collection set, that these 5275 // reference objects point to may not have been copied: the STW ref 5276 // processor would have seen that the reference object had already 5277 // been 'discovered' and would have skipped discovering the reference, 5278 // but would not have treated the reference object as a regular oop. 5279 // As a result the copy closure would not have been applied to the 5280 // referent object. 5281 // 5282 // We need to explicitly copy these referent objects - the references 5283 // will be processed at the end of remarking. 5284 // 5285 // We also need to do this copying before we process the reference 5286 // objects discovered by the STW ref processor in case one of these 5287 // referents points to another object which is also referenced by an 5288 // object discovered by the STW ref processor. 5289 5290 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5291 5292 set_par_threads(no_of_gc_workers); 5293 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5294 no_of_gc_workers, 5295 _task_queues); 5296 5297 workers()->run_task(&keep_cm_referents); 5298 5299 set_par_threads(0); 5300 5301 // Closure to test whether a referent is alive. 5302 G1STWIsAliveClosure is_alive(this); 5303 5304 // Even when parallel reference processing is enabled, the processing 5305 // of JNI refs is serial and performed serially by the current thread 5306 // rather than by a worker. The following PSS will be used for processing 5307 // JNI refs. 5308 5309 // Use only a single queue for this PSS. 5310 G1ParScanThreadState pss(this, 0, NULL); 5311 5312 // We do not embed a reference processor in the copying/scanning 5313 // closures while we're actually processing the discovered 5314 // reference objects. 5315 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5316 5317 pss.set_evac_failure_closure(&evac_failure_cl); 5318 5319 assert(pss.queue_is_empty(), "pre-condition"); 5320 5321 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5322 5323 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5324 5325 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5326 5327 if (g1_policy()->during_initial_mark_pause()) { 5328 // We also need to mark copied objects. 5329 copy_non_heap_cl = ©_mark_non_heap_cl; 5330 } 5331 5332 // Keep alive closure. 5333 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5334 5335 // Serial Complete GC closure 5336 G1STWDrainQueueClosure drain_queue(this, &pss); 5337 5338 // Setup the soft refs policy... 5339 rp->setup_policy(false); 5340 5341 ReferenceProcessorStats stats; 5342 if (!rp->processing_is_mt()) { 5343 // Serial reference processing... 5344 stats = rp->process_discovered_references(&is_alive, 5345 &keep_alive, 5346 &drain_queue, 5347 NULL, 5348 _gc_timer_stw, 5349 _gc_tracer_stw->gc_id()); 5350 } else { 5351 // Parallel reference processing 5352 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5353 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5354 5355 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5356 stats = rp->process_discovered_references(&is_alive, 5357 &keep_alive, 5358 &drain_queue, 5359 &par_task_executor, 5360 _gc_timer_stw, 5361 _gc_tracer_stw->gc_id()); 5362 } 5363 5364 _gc_tracer_stw->report_gc_reference_stats(stats); 5365 5366 // We have completed copying any necessary live referent objects. 5367 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5368 5369 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5370 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5371 } 5372 5373 // Weak Reference processing during an evacuation pause (part 2). 5374 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5375 double ref_enq_start = os::elapsedTime(); 5376 5377 ReferenceProcessor* rp = _ref_processor_stw; 5378 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5379 5380 // Now enqueue any remaining on the discovered lists on to 5381 // the pending list. 5382 if (!rp->processing_is_mt()) { 5383 // Serial reference processing... 5384 rp->enqueue_discovered_references(); 5385 } else { 5386 // Parallel reference enqueueing 5387 5388 assert(no_of_gc_workers == workers()->active_workers(), 5389 "Need to reset active workers"); 5390 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5391 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5392 5393 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5394 rp->enqueue_discovered_references(&par_task_executor); 5395 } 5396 5397 rp->verify_no_references_recorded(); 5398 assert(!rp->discovery_enabled(), "should have been disabled"); 5399 5400 // FIXME 5401 // CM's reference processing also cleans up the string and symbol tables. 5402 // Should we do that here also? We could, but it is a serial operation 5403 // and could significantly increase the pause time. 5404 5405 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5406 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5407 } 5408 5409 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5410 _expand_heap_after_alloc_failure = true; 5411 _evacuation_failed = false; 5412 5413 // Should G1EvacuationFailureALot be in effect for this GC? 5414 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5415 5416 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5417 5418 // Disable the hot card cache. 5419 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5420 hot_card_cache->reset_hot_cache_claimed_index(); 5421 hot_card_cache->set_use_cache(false); 5422 5423 const uint n_workers = workers()->active_workers(); 5424 assert(UseDynamicNumberOfGCThreads || 5425 n_workers == workers()->total_workers(), 5426 "If not dynamic should be using all the workers"); 5427 set_par_threads(n_workers); 5428 5429 5430 init_for_evac_failure(NULL); 5431 5432 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5433 double start_par_time_sec = os::elapsedTime(); 5434 double end_par_time_sec; 5435 5436 { 5437 G1RootProcessor root_processor(this); 5438 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5439 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5440 if (g1_policy()->during_initial_mark_pause()) { 5441 ClassLoaderDataGraph::clear_claimed_marks(); 5442 } 5443 5444 // The individual threads will set their evac-failure closures. 5445 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5446 // These tasks use ShareHeap::_process_strong_tasks 5447 assert(UseDynamicNumberOfGCThreads || 5448 workers()->active_workers() == workers()->total_workers(), 5449 "If not dynamic should be using all the workers"); 5450 workers()->run_task(&g1_par_task); 5451 end_par_time_sec = os::elapsedTime(); 5452 5453 // Closing the inner scope will execute the destructor 5454 // for the G1RootProcessor object. We record the current 5455 // elapsed time before closing the scope so that time 5456 // taken for the destructor is NOT included in the 5457 // reported parallel time. 5458 } 5459 5460 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5461 5462 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5463 phase_times->record_par_time(par_time_ms); 5464 5465 double code_root_fixup_time_ms = 5466 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5467 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5468 5469 set_par_threads(0); 5470 5471 // Process any discovered reference objects - we have 5472 // to do this _before_ we retire the GC alloc regions 5473 // as we may have to copy some 'reachable' referent 5474 // objects (and their reachable sub-graphs) that were 5475 // not copied during the pause. 5476 process_discovered_references(n_workers); 5477 5478 if (G1StringDedup::is_enabled()) { 5479 double fixup_start = os::elapsedTime(); 5480 5481 G1STWIsAliveClosure is_alive(this); 5482 G1KeepAliveClosure keep_alive(this); 5483 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5484 5485 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5486 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5487 } 5488 5489 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5490 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5491 5492 // Reset and re-enable the hot card cache. 5493 // Note the counts for the cards in the regions in the 5494 // collection set are reset when the collection set is freed. 5495 hot_card_cache->reset_hot_cache(); 5496 hot_card_cache->set_use_cache(true); 5497 5498 purge_code_root_memory(); 5499 5500 finalize_for_evac_failure(); 5501 5502 if (evacuation_failed()) { 5503 remove_self_forwarding_pointers(); 5504 5505 // Reset the G1EvacuationFailureALot counters and flags 5506 // Note: the values are reset only when an actual 5507 // evacuation failure occurs. 5508 NOT_PRODUCT(reset_evacuation_should_fail();) 5509 } 5510 5511 // Enqueue any remaining references remaining on the STW 5512 // reference processor's discovered lists. We need to do 5513 // this after the card table is cleaned (and verified) as 5514 // the act of enqueueing entries on to the pending list 5515 // will log these updates (and dirty their associated 5516 // cards). We need these updates logged to update any 5517 // RSets. 5518 enqueue_discovered_references(n_workers); 5519 5520 redirty_logged_cards(); 5521 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5522 } 5523 5524 void G1CollectedHeap::free_region(HeapRegion* hr, 5525 FreeRegionList* free_list, 5526 bool par, 5527 bool locked) { 5528 assert(!hr->is_free(), "the region should not be free"); 5529 assert(!hr->is_empty(), "the region should not be empty"); 5530 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5531 assert(free_list != NULL, "pre-condition"); 5532 5533 if (G1VerifyBitmaps) { 5534 MemRegion mr(hr->bottom(), hr->end()); 5535 concurrent_mark()->clearRangePrevBitmap(mr); 5536 } 5537 5538 // Clear the card counts for this region. 5539 // Note: we only need to do this if the region is not young 5540 // (since we don't refine cards in young regions). 5541 if (!hr->is_young()) { 5542 _cg1r->hot_card_cache()->reset_card_counts(hr); 5543 } 5544 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5545 free_list->add_ordered(hr); 5546 } 5547 5548 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5549 FreeRegionList* free_list, 5550 bool par) { 5551 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5552 assert(free_list != NULL, "pre-condition"); 5553 5554 size_t hr_capacity = hr->capacity(); 5555 // We need to read this before we make the region non-humongous, 5556 // otherwise the information will be gone. 5557 uint last_index = hr->last_hc_index(); 5558 hr->clear_humongous(); 5559 free_region(hr, free_list, par); 5560 5561 uint i = hr->hrm_index() + 1; 5562 while (i < last_index) { 5563 HeapRegion* curr_hr = region_at(i); 5564 assert(curr_hr->is_continues_humongous(), "invariant"); 5565 curr_hr->clear_humongous(); 5566 free_region(curr_hr, free_list, par); 5567 i += 1; 5568 } 5569 } 5570 5571 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5572 const HeapRegionSetCount& humongous_regions_removed) { 5573 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5574 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5575 _old_set.bulk_remove(old_regions_removed); 5576 _humongous_set.bulk_remove(humongous_regions_removed); 5577 } 5578 5579 } 5580 5581 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5582 assert(list != NULL, "list can't be null"); 5583 if (!list->is_empty()) { 5584 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5585 _hrm.insert_list_into_free_list(list); 5586 } 5587 } 5588 5589 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5590 _allocator->decrease_used(bytes); 5591 } 5592 5593 class G1ParCleanupCTTask : public AbstractGangTask { 5594 G1SATBCardTableModRefBS* _ct_bs; 5595 G1CollectedHeap* _g1h; 5596 HeapRegion* volatile _su_head; 5597 public: 5598 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5599 G1CollectedHeap* g1h) : 5600 AbstractGangTask("G1 Par Cleanup CT Task"), 5601 _ct_bs(ct_bs), _g1h(g1h) { } 5602 5603 void work(uint worker_id) { 5604 HeapRegion* r; 5605 while (r = _g1h->pop_dirty_cards_region()) { 5606 clear_cards(r); 5607 } 5608 } 5609 5610 void clear_cards(HeapRegion* r) { 5611 // Cards of the survivors should have already been dirtied. 5612 if (!r->is_survivor()) { 5613 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5614 } 5615 } 5616 }; 5617 5618 #ifndef PRODUCT 5619 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5620 G1CollectedHeap* _g1h; 5621 G1SATBCardTableModRefBS* _ct_bs; 5622 public: 5623 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5624 : _g1h(g1h), _ct_bs(ct_bs) { } 5625 virtual bool doHeapRegion(HeapRegion* r) { 5626 if (r->is_survivor()) { 5627 _g1h->verify_dirty_region(r); 5628 } else { 5629 _g1h->verify_not_dirty_region(r); 5630 } 5631 return false; 5632 } 5633 }; 5634 5635 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5636 // All of the region should be clean. 5637 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5638 MemRegion mr(hr->bottom(), hr->end()); 5639 ct_bs->verify_not_dirty_region(mr); 5640 } 5641 5642 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5643 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5644 // dirty allocated blocks as they allocate them. The thread that 5645 // retires each region and replaces it with a new one will do a 5646 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5647 // not dirty that area (one less thing to have to do while holding 5648 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5649 // is dirty. 5650 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5651 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5652 if (hr->is_young()) { 5653 ct_bs->verify_g1_young_region(mr); 5654 } else { 5655 ct_bs->verify_dirty_region(mr); 5656 } 5657 } 5658 5659 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5660 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5661 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5662 verify_dirty_region(hr); 5663 } 5664 } 5665 5666 void G1CollectedHeap::verify_dirty_young_regions() { 5667 verify_dirty_young_list(_young_list->first_region()); 5668 } 5669 5670 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5671 HeapWord* tams, HeapWord* end) { 5672 guarantee(tams <= end, 5673 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end))); 5674 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5675 if (result < end) { 5676 gclog_or_tty->cr(); 5677 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5678 bitmap_name, p2i(result)); 5679 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5680 bitmap_name, p2i(tams), p2i(end)); 5681 return false; 5682 } 5683 return true; 5684 } 5685 5686 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5687 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5688 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5689 5690 HeapWord* bottom = hr->bottom(); 5691 HeapWord* ptams = hr->prev_top_at_mark_start(); 5692 HeapWord* ntams = hr->next_top_at_mark_start(); 5693 HeapWord* end = hr->end(); 5694 5695 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5696 5697 bool res_n = true; 5698 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5699 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5700 // if we happen to be in that state. 5701 if (mark_in_progress() || !_cmThread->in_progress()) { 5702 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5703 } 5704 if (!res_p || !res_n) { 5705 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5706 HR_FORMAT_PARAMS(hr)); 5707 gclog_or_tty->print_cr("#### Caller: %s", caller); 5708 return false; 5709 } 5710 return true; 5711 } 5712 5713 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5714 if (!G1VerifyBitmaps) return; 5715 5716 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5717 } 5718 5719 class G1VerifyBitmapClosure : public HeapRegionClosure { 5720 private: 5721 const char* _caller; 5722 G1CollectedHeap* _g1h; 5723 bool _failures; 5724 5725 public: 5726 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5727 _caller(caller), _g1h(g1h), _failures(false) { } 5728 5729 bool failures() { return _failures; } 5730 5731 virtual bool doHeapRegion(HeapRegion* hr) { 5732 if (hr->is_continues_humongous()) return false; 5733 5734 bool result = _g1h->verify_bitmaps(_caller, hr); 5735 if (!result) { 5736 _failures = true; 5737 } 5738 return false; 5739 } 5740 }; 5741 5742 void G1CollectedHeap::check_bitmaps(const char* caller) { 5743 if (!G1VerifyBitmaps) return; 5744 5745 G1VerifyBitmapClosure cl(caller, this); 5746 heap_region_iterate(&cl); 5747 guarantee(!cl.failures(), "bitmap verification"); 5748 } 5749 5750 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5751 private: 5752 bool _failures; 5753 public: 5754 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5755 5756 virtual bool doHeapRegion(HeapRegion* hr) { 5757 uint i = hr->hrm_index(); 5758 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5759 if (hr->is_humongous()) { 5760 if (hr->in_collection_set()) { 5761 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5762 _failures = true; 5763 return true; 5764 } 5765 if (cset_state.is_in_cset()) { 5766 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5767 _failures = true; 5768 return true; 5769 } 5770 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5771 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5772 _failures = true; 5773 return true; 5774 } 5775 } else { 5776 if (cset_state.is_humongous()) { 5777 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5778 _failures = true; 5779 return true; 5780 } 5781 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5782 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5783 hr->in_collection_set(), cset_state.value(), i); 5784 _failures = true; 5785 return true; 5786 } 5787 if (cset_state.is_in_cset()) { 5788 if (hr->is_young() != (cset_state.is_young())) { 5789 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5790 hr->is_young(), cset_state.value(), i); 5791 _failures = true; 5792 return true; 5793 } 5794 if (hr->is_old() != (cset_state.is_old())) { 5795 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5796 hr->is_old(), cset_state.value(), i); 5797 _failures = true; 5798 return true; 5799 } 5800 } 5801 } 5802 return false; 5803 } 5804 5805 bool failures() const { return _failures; } 5806 }; 5807 5808 bool G1CollectedHeap::check_cset_fast_test() { 5809 G1CheckCSetFastTableClosure cl; 5810 _hrm.iterate(&cl); 5811 return !cl.failures(); 5812 } 5813 #endif // PRODUCT 5814 5815 void G1CollectedHeap::cleanUpCardTable() { 5816 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5817 double start = os::elapsedTime(); 5818 5819 { 5820 // Iterate over the dirty cards region list. 5821 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5822 5823 set_par_threads(); 5824 workers()->run_task(&cleanup_task); 5825 set_par_threads(0); 5826 #ifndef PRODUCT 5827 if (G1VerifyCTCleanup || VerifyAfterGC) { 5828 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5829 heap_region_iterate(&cleanup_verifier); 5830 } 5831 #endif 5832 } 5833 5834 double elapsed = os::elapsedTime() - start; 5835 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5836 } 5837 5838 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5839 size_t pre_used = 0; 5840 FreeRegionList local_free_list("Local List for CSet Freeing"); 5841 5842 double young_time_ms = 0.0; 5843 double non_young_time_ms = 0.0; 5844 5845 // Since the collection set is a superset of the the young list, 5846 // all we need to do to clear the young list is clear its 5847 // head and length, and unlink any young regions in the code below 5848 _young_list->clear(); 5849 5850 G1CollectorPolicy* policy = g1_policy(); 5851 5852 double start_sec = os::elapsedTime(); 5853 bool non_young = true; 5854 5855 HeapRegion* cur = cs_head; 5856 int age_bound = -1; 5857 size_t rs_lengths = 0; 5858 5859 while (cur != NULL) { 5860 assert(!is_on_master_free_list(cur), "sanity"); 5861 if (non_young) { 5862 if (cur->is_young()) { 5863 double end_sec = os::elapsedTime(); 5864 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5865 non_young_time_ms += elapsed_ms; 5866 5867 start_sec = os::elapsedTime(); 5868 non_young = false; 5869 } 5870 } else { 5871 if (!cur->is_young()) { 5872 double end_sec = os::elapsedTime(); 5873 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5874 young_time_ms += elapsed_ms; 5875 5876 start_sec = os::elapsedTime(); 5877 non_young = true; 5878 } 5879 } 5880 5881 rs_lengths += cur->rem_set()->occupied_locked(); 5882 5883 HeapRegion* next = cur->next_in_collection_set(); 5884 assert(cur->in_collection_set(), "bad CS"); 5885 cur->set_next_in_collection_set(NULL); 5886 clear_in_cset(cur); 5887 5888 if (cur->is_young()) { 5889 int index = cur->young_index_in_cset(); 5890 assert(index != -1, "invariant"); 5891 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5892 size_t words_survived = _surviving_young_words[index]; 5893 cur->record_surv_words_in_group(words_survived); 5894 5895 // At this point the we have 'popped' cur from the collection set 5896 // (linked via next_in_collection_set()) but it is still in the 5897 // young list (linked via next_young_region()). Clear the 5898 // _next_young_region field. 5899 cur->set_next_young_region(NULL); 5900 } else { 5901 int index = cur->young_index_in_cset(); 5902 assert(index == -1, "invariant"); 5903 } 5904 5905 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5906 (!cur->is_young() && cur->young_index_in_cset() == -1), 5907 "invariant" ); 5908 5909 if (!cur->evacuation_failed()) { 5910 MemRegion used_mr = cur->used_region(); 5911 5912 // And the region is empty. 5913 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5914 pre_used += cur->used(); 5915 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5916 } else { 5917 cur->uninstall_surv_rate_group(); 5918 if (cur->is_young()) { 5919 cur->set_young_index_in_cset(-1); 5920 } 5921 cur->set_evacuation_failed(false); 5922 // The region is now considered to be old. 5923 cur->set_old(); 5924 _old_set.add(cur); 5925 evacuation_info.increment_collectionset_used_after(cur->used()); 5926 } 5927 cur = next; 5928 } 5929 5930 evacuation_info.set_regions_freed(local_free_list.length()); 5931 policy->record_max_rs_lengths(rs_lengths); 5932 policy->cset_regions_freed(); 5933 5934 double end_sec = os::elapsedTime(); 5935 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5936 5937 if (non_young) { 5938 non_young_time_ms += elapsed_ms; 5939 } else { 5940 young_time_ms += elapsed_ms; 5941 } 5942 5943 prepend_to_freelist(&local_free_list); 5944 decrement_summary_bytes(pre_used); 5945 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5946 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5947 } 5948 5949 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5950 private: 5951 FreeRegionList* _free_region_list; 5952 HeapRegionSet* _proxy_set; 5953 HeapRegionSetCount _humongous_regions_removed; 5954 size_t _freed_bytes; 5955 public: 5956 5957 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5958 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5959 } 5960 5961 virtual bool doHeapRegion(HeapRegion* r) { 5962 if (!r->is_starts_humongous()) { 5963 return false; 5964 } 5965 5966 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5967 5968 oop obj = (oop)r->bottom(); 5969 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5970 5971 // The following checks whether the humongous object is live are sufficient. 5972 // The main additional check (in addition to having a reference from the roots 5973 // or the young gen) is whether the humongous object has a remembered set entry. 5974 // 5975 // A humongous object cannot be live if there is no remembered set for it 5976 // because: 5977 // - there can be no references from within humongous starts regions referencing 5978 // the object because we never allocate other objects into them. 5979 // (I.e. there are no intra-region references that may be missed by the 5980 // remembered set) 5981 // - as soon there is a remembered set entry to the humongous starts region 5982 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5983 // until the end of a concurrent mark. 5984 // 5985 // It is not required to check whether the object has been found dead by marking 5986 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5987 // all objects allocated during that time are considered live. 5988 // SATB marking is even more conservative than the remembered set. 5989 // So if at this point in the collection there is no remembered set entry, 5990 // nobody has a reference to it. 5991 // At the start of collection we flush all refinement logs, and remembered sets 5992 // are completely up-to-date wrt to references to the humongous object. 5993 // 5994 // Other implementation considerations: 5995 // - never consider object arrays at this time because they would pose 5996 // considerable effort for cleaning up the the remembered sets. This is 5997 // required because stale remembered sets might reference locations that 5998 // are currently allocated into. 5999 uint region_idx = r->hrm_index(); 6000 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6001 !r->rem_set()->is_empty()) { 6002 6003 if (G1TraceEagerReclaimHumongousObjects) { 6004 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", 6005 region_idx, 6006 (size_t)obj->size() * HeapWordSize, 6007 p2i(r->bottom()), 6008 r->region_num(), 6009 r->rem_set()->occupied(), 6010 r->rem_set()->strong_code_roots_list_length(), 6011 next_bitmap->isMarked(r->bottom()), 6012 g1h->is_humongous_reclaim_candidate(region_idx), 6013 obj->is_typeArray() 6014 ); 6015 } 6016 6017 return false; 6018 } 6019 6020 guarantee(obj->is_typeArray(), 6021 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6022 PTR_FORMAT " is not.", 6023 p2i(r->bottom()))); 6024 6025 if (G1TraceEagerReclaimHumongousObjects) { 6026 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", 6027 region_idx, 6028 (size_t)obj->size() * HeapWordSize, 6029 p2i(r->bottom()), 6030 r->region_num(), 6031 r->rem_set()->occupied(), 6032 r->rem_set()->strong_code_roots_list_length(), 6033 next_bitmap->isMarked(r->bottom()), 6034 g1h->is_humongous_reclaim_candidate(region_idx), 6035 obj->is_typeArray() 6036 ); 6037 } 6038 // Need to clear mark bit of the humongous object if already set. 6039 if (next_bitmap->isMarked(r->bottom())) { 6040 next_bitmap->clear(r->bottom()); 6041 } 6042 _freed_bytes += r->used(); 6043 r->set_containing_set(NULL); 6044 _humongous_regions_removed.increment(1u, r->capacity()); 6045 g1h->free_humongous_region(r, _free_region_list, false); 6046 6047 return false; 6048 } 6049 6050 HeapRegionSetCount& humongous_free_count() { 6051 return _humongous_regions_removed; 6052 } 6053 6054 size_t bytes_freed() const { 6055 return _freed_bytes; 6056 } 6057 6058 size_t humongous_reclaimed() const { 6059 return _humongous_regions_removed.length(); 6060 } 6061 }; 6062 6063 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6064 assert_at_safepoint(true); 6065 6066 if (!G1EagerReclaimHumongousObjects || 6067 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6068 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6069 return; 6070 } 6071 6072 double start_time = os::elapsedTime(); 6073 6074 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6075 6076 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6077 heap_region_iterate(&cl); 6078 6079 HeapRegionSetCount empty_set; 6080 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6081 6082 G1HRPrinter* hrp = hr_printer(); 6083 if (hrp->is_active()) { 6084 FreeRegionListIterator iter(&local_cleanup_list); 6085 while (iter.more_available()) { 6086 HeapRegion* hr = iter.get_next(); 6087 hrp->cleanup(hr); 6088 } 6089 } 6090 6091 prepend_to_freelist(&local_cleanup_list); 6092 decrement_summary_bytes(cl.bytes_freed()); 6093 6094 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6095 cl.humongous_reclaimed()); 6096 } 6097 6098 // This routine is similar to the above but does not record 6099 // any policy statistics or update free lists; we are abandoning 6100 // the current incremental collection set in preparation of a 6101 // full collection. After the full GC we will start to build up 6102 // the incremental collection set again. 6103 // This is only called when we're doing a full collection 6104 // and is immediately followed by the tearing down of the young list. 6105 6106 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6107 HeapRegion* cur = cs_head; 6108 6109 while (cur != NULL) { 6110 HeapRegion* next = cur->next_in_collection_set(); 6111 assert(cur->in_collection_set(), "bad CS"); 6112 cur->set_next_in_collection_set(NULL); 6113 clear_in_cset(cur); 6114 cur->set_young_index_in_cset(-1); 6115 cur = next; 6116 } 6117 } 6118 6119 void G1CollectedHeap::set_free_regions_coming() { 6120 if (G1ConcRegionFreeingVerbose) { 6121 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6122 "setting free regions coming"); 6123 } 6124 6125 assert(!free_regions_coming(), "pre-condition"); 6126 _free_regions_coming = true; 6127 } 6128 6129 void G1CollectedHeap::reset_free_regions_coming() { 6130 assert(free_regions_coming(), "pre-condition"); 6131 6132 { 6133 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6134 _free_regions_coming = false; 6135 SecondaryFreeList_lock->notify_all(); 6136 } 6137 6138 if (G1ConcRegionFreeingVerbose) { 6139 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6140 "reset free regions coming"); 6141 } 6142 } 6143 6144 void G1CollectedHeap::wait_while_free_regions_coming() { 6145 // Most of the time we won't have to wait, so let's do a quick test 6146 // first before we take the lock. 6147 if (!free_regions_coming()) { 6148 return; 6149 } 6150 6151 if (G1ConcRegionFreeingVerbose) { 6152 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6153 "waiting for free regions"); 6154 } 6155 6156 { 6157 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6158 while (free_regions_coming()) { 6159 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6160 } 6161 } 6162 6163 if (G1ConcRegionFreeingVerbose) { 6164 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6165 "done waiting for free regions"); 6166 } 6167 } 6168 6169 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6170 _young_list->push_region(hr); 6171 } 6172 6173 class NoYoungRegionsClosure: public HeapRegionClosure { 6174 private: 6175 bool _success; 6176 public: 6177 NoYoungRegionsClosure() : _success(true) { } 6178 bool doHeapRegion(HeapRegion* r) { 6179 if (r->is_young()) { 6180 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6181 p2i(r->bottom()), p2i(r->end())); 6182 _success = false; 6183 } 6184 return false; 6185 } 6186 bool success() { return _success; } 6187 }; 6188 6189 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6190 bool ret = _young_list->check_list_empty(check_sample); 6191 6192 if (check_heap) { 6193 NoYoungRegionsClosure closure; 6194 heap_region_iterate(&closure); 6195 ret = ret && closure.success(); 6196 } 6197 6198 return ret; 6199 } 6200 6201 class TearDownRegionSetsClosure : public HeapRegionClosure { 6202 private: 6203 HeapRegionSet *_old_set; 6204 6205 public: 6206 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6207 6208 bool doHeapRegion(HeapRegion* r) { 6209 if (r->is_old()) { 6210 _old_set->remove(r); 6211 } else { 6212 // We ignore free regions, we'll empty the free list afterwards. 6213 // We ignore young regions, we'll empty the young list afterwards. 6214 // We ignore humongous regions, we're not tearing down the 6215 // humongous regions set. 6216 assert(r->is_free() || r->is_young() || r->is_humongous(), 6217 "it cannot be another type"); 6218 } 6219 return false; 6220 } 6221 6222 ~TearDownRegionSetsClosure() { 6223 assert(_old_set->is_empty(), "post-condition"); 6224 } 6225 }; 6226 6227 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6228 assert_at_safepoint(true /* should_be_vm_thread */); 6229 6230 if (!free_list_only) { 6231 TearDownRegionSetsClosure cl(&_old_set); 6232 heap_region_iterate(&cl); 6233 6234 // Note that emptying the _young_list is postponed and instead done as 6235 // the first step when rebuilding the regions sets again. The reason for 6236 // this is that during a full GC string deduplication needs to know if 6237 // a collected region was young or old when the full GC was initiated. 6238 } 6239 _hrm.remove_all_free_regions(); 6240 } 6241 6242 class RebuildRegionSetsClosure : public HeapRegionClosure { 6243 private: 6244 bool _free_list_only; 6245 HeapRegionSet* _old_set; 6246 HeapRegionManager* _hrm; 6247 size_t _total_used; 6248 6249 public: 6250 RebuildRegionSetsClosure(bool free_list_only, 6251 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6252 _free_list_only(free_list_only), 6253 _old_set(old_set), _hrm(hrm), _total_used(0) { 6254 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6255 if (!free_list_only) { 6256 assert(_old_set->is_empty(), "pre-condition"); 6257 } 6258 } 6259 6260 bool doHeapRegion(HeapRegion* r) { 6261 if (r->is_continues_humongous()) { 6262 return false; 6263 } 6264 6265 if (r->is_empty()) { 6266 // Add free regions to the free list 6267 r->set_free(); 6268 r->set_allocation_context(AllocationContext::system()); 6269 _hrm->insert_into_free_list(r); 6270 } else if (!_free_list_only) { 6271 assert(!r->is_young(), "we should not come across young regions"); 6272 6273 if (r->is_humongous()) { 6274 // We ignore humongous regions, we left the humongous set unchanged 6275 } else { 6276 // Objects that were compacted would have ended up on regions 6277 // that were previously old or free. 6278 assert(r->is_free() || r->is_old(), "invariant"); 6279 // We now consider them old, so register as such. 6280 r->set_old(); 6281 _old_set->add(r); 6282 } 6283 _total_used += r->used(); 6284 } 6285 6286 return false; 6287 } 6288 6289 size_t total_used() { 6290 return _total_used; 6291 } 6292 }; 6293 6294 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6295 assert_at_safepoint(true /* should_be_vm_thread */); 6296 6297 if (!free_list_only) { 6298 _young_list->empty_list(); 6299 } 6300 6301 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6302 heap_region_iterate(&cl); 6303 6304 if (!free_list_only) { 6305 _allocator->set_used(cl.total_used()); 6306 } 6307 assert(_allocator->used_unlocked() == recalculate_used(), 6308 err_msg("inconsistent _allocator->used_unlocked(), " 6309 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6310 _allocator->used_unlocked(), recalculate_used())); 6311 } 6312 6313 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6314 _refine_cte_cl->set_concurrent(concurrent); 6315 } 6316 6317 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6318 HeapRegion* hr = heap_region_containing(p); 6319 return hr->is_in(p); 6320 } 6321 6322 // Methods for the mutator alloc region 6323 6324 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6325 bool force) { 6326 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6327 assert(!force || g1_policy()->can_expand_young_list(), 6328 "if force is true we should be able to expand the young list"); 6329 bool young_list_full = g1_policy()->is_young_list_full(); 6330 if (force || !young_list_full) { 6331 HeapRegion* new_alloc_region = new_region(word_size, 6332 false /* is_old */, 6333 false /* do_expand */); 6334 if (new_alloc_region != NULL) { 6335 set_region_short_lived_locked(new_alloc_region); 6336 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6337 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6338 return new_alloc_region; 6339 } 6340 } 6341 return NULL; 6342 } 6343 6344 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6345 size_t allocated_bytes) { 6346 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6347 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6348 6349 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6350 _allocator->increase_used(allocated_bytes); 6351 _hr_printer.retire(alloc_region); 6352 // We update the eden sizes here, when the region is retired, 6353 // instead of when it's allocated, since this is the point that its 6354 // used space has been recored in _summary_bytes_used. 6355 g1mm()->update_eden_size(); 6356 } 6357 6358 void G1CollectedHeap::set_par_threads() { 6359 // Don't change the number of workers. Use the value previously set 6360 // in the workgroup. 6361 uint n_workers = workers()->active_workers(); 6362 assert(UseDynamicNumberOfGCThreads || 6363 n_workers == workers()->total_workers(), 6364 "Otherwise should be using the total number of workers"); 6365 if (n_workers == 0) { 6366 assert(false, "Should have been set in prior evacuation pause."); 6367 n_workers = ParallelGCThreads; 6368 workers()->set_active_workers(n_workers); 6369 } 6370 set_par_threads(n_workers); 6371 } 6372 6373 // Methods for the GC alloc regions 6374 6375 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6376 uint count, 6377 InCSetState dest) { 6378 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6379 6380 if (count < g1_policy()->max_regions(dest)) { 6381 const bool is_survivor = (dest.is_young()); 6382 HeapRegion* new_alloc_region = new_region(word_size, 6383 !is_survivor, 6384 true /* do_expand */); 6385 if (new_alloc_region != NULL) { 6386 // We really only need to do this for old regions given that we 6387 // should never scan survivors. But it doesn't hurt to do it 6388 // for survivors too. 6389 new_alloc_region->record_timestamp(); 6390 if (is_survivor) { 6391 new_alloc_region->set_survivor(); 6392 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6393 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6394 } else { 6395 new_alloc_region->set_old(); 6396 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6397 check_bitmaps("Old Region Allocation", new_alloc_region); 6398 } 6399 bool during_im = g1_policy()->during_initial_mark_pause(); 6400 new_alloc_region->note_start_of_copying(during_im); 6401 return new_alloc_region; 6402 } 6403 } 6404 return NULL; 6405 } 6406 6407 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6408 size_t allocated_bytes, 6409 InCSetState dest) { 6410 bool during_im = g1_policy()->during_initial_mark_pause(); 6411 alloc_region->note_end_of_copying(during_im); 6412 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6413 if (dest.is_young()) { 6414 young_list()->add_survivor_region(alloc_region); 6415 } else { 6416 _old_set.add(alloc_region); 6417 } 6418 _hr_printer.retire(alloc_region); 6419 } 6420 6421 // Heap region set verification 6422 6423 class VerifyRegionListsClosure : public HeapRegionClosure { 6424 private: 6425 HeapRegionSet* _old_set; 6426 HeapRegionSet* _humongous_set; 6427 HeapRegionManager* _hrm; 6428 6429 public: 6430 HeapRegionSetCount _old_count; 6431 HeapRegionSetCount _humongous_count; 6432 HeapRegionSetCount _free_count; 6433 6434 VerifyRegionListsClosure(HeapRegionSet* old_set, 6435 HeapRegionSet* humongous_set, 6436 HeapRegionManager* hrm) : 6437 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6438 _old_count(), _humongous_count(), _free_count(){ } 6439 6440 bool doHeapRegion(HeapRegion* hr) { 6441 if (hr->is_continues_humongous()) { 6442 return false; 6443 } 6444 6445 if (hr->is_young()) { 6446 // TODO 6447 } else if (hr->is_starts_humongous()) { 6448 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6449 _humongous_count.increment(1u, hr->capacity()); 6450 } else if (hr->is_empty()) { 6451 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6452 _free_count.increment(1u, hr->capacity()); 6453 } else if (hr->is_old()) { 6454 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6455 _old_count.increment(1u, hr->capacity()); 6456 } else { 6457 ShouldNotReachHere(); 6458 } 6459 return false; 6460 } 6461 6462 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6463 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6464 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6465 old_set->total_capacity_bytes(), _old_count.capacity())); 6466 6467 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6468 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6469 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6470 6471 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length())); 6472 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6473 free_list->total_capacity_bytes(), _free_count.capacity())); 6474 } 6475 }; 6476 6477 void G1CollectedHeap::verify_region_sets() { 6478 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6479 6480 // First, check the explicit lists. 6481 _hrm.verify(); 6482 { 6483 // Given that a concurrent operation might be adding regions to 6484 // the secondary free list we have to take the lock before 6485 // verifying it. 6486 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6487 _secondary_free_list.verify_list(); 6488 } 6489 6490 // If a concurrent region freeing operation is in progress it will 6491 // be difficult to correctly attributed any free regions we come 6492 // across to the correct free list given that they might belong to 6493 // one of several (free_list, secondary_free_list, any local lists, 6494 // etc.). So, if that's the case we will skip the rest of the 6495 // verification operation. Alternatively, waiting for the concurrent 6496 // operation to complete will have a non-trivial effect on the GC's 6497 // operation (no concurrent operation will last longer than the 6498 // interval between two calls to verification) and it might hide 6499 // any issues that we would like to catch during testing. 6500 if (free_regions_coming()) { 6501 return; 6502 } 6503 6504 // Make sure we append the secondary_free_list on the free_list so 6505 // that all free regions we will come across can be safely 6506 // attributed to the free_list. 6507 append_secondary_free_list_if_not_empty_with_lock(); 6508 6509 // Finally, make sure that the region accounting in the lists is 6510 // consistent with what we see in the heap. 6511 6512 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6513 heap_region_iterate(&cl); 6514 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6515 } 6516 6517 // Optimized nmethod scanning 6518 6519 class RegisterNMethodOopClosure: public OopClosure { 6520 G1CollectedHeap* _g1h; 6521 nmethod* _nm; 6522 6523 template <class T> void do_oop_work(T* p) { 6524 T heap_oop = oopDesc::load_heap_oop(p); 6525 if (!oopDesc::is_null(heap_oop)) { 6526 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6527 HeapRegion* hr = _g1h->heap_region_containing(obj); 6528 assert(!hr->is_continues_humongous(), 6529 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6530 " starting at "HR_FORMAT, 6531 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6532 6533 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6534 hr->add_strong_code_root_locked(_nm); 6535 } 6536 } 6537 6538 public: 6539 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6540 _g1h(g1h), _nm(nm) {} 6541 6542 void do_oop(oop* p) { do_oop_work(p); } 6543 void do_oop(narrowOop* p) { do_oop_work(p); } 6544 }; 6545 6546 class UnregisterNMethodOopClosure: public OopClosure { 6547 G1CollectedHeap* _g1h; 6548 nmethod* _nm; 6549 6550 template <class T> void do_oop_work(T* p) { 6551 T heap_oop = oopDesc::load_heap_oop(p); 6552 if (!oopDesc::is_null(heap_oop)) { 6553 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6554 HeapRegion* hr = _g1h->heap_region_containing(obj); 6555 assert(!hr->is_continues_humongous(), 6556 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6557 " starting at "HR_FORMAT, 6558 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6559 6560 hr->remove_strong_code_root(_nm); 6561 } 6562 } 6563 6564 public: 6565 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6566 _g1h(g1h), _nm(nm) {} 6567 6568 void do_oop(oop* p) { do_oop_work(p); } 6569 void do_oop(narrowOop* p) { do_oop_work(p); } 6570 }; 6571 6572 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6573 CollectedHeap::register_nmethod(nm); 6574 6575 guarantee(nm != NULL, "sanity"); 6576 RegisterNMethodOopClosure reg_cl(this, nm); 6577 nm->oops_do(®_cl); 6578 } 6579 6580 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6581 CollectedHeap::unregister_nmethod(nm); 6582 6583 guarantee(nm != NULL, "sanity"); 6584 UnregisterNMethodOopClosure reg_cl(this, nm); 6585 nm->oops_do(®_cl, true); 6586 } 6587 6588 void G1CollectedHeap::purge_code_root_memory() { 6589 double purge_start = os::elapsedTime(); 6590 G1CodeRootSet::purge(); 6591 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6592 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6593 } 6594 6595 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6596 G1CollectedHeap* _g1h; 6597 6598 public: 6599 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6600 _g1h(g1h) {} 6601 6602 void do_code_blob(CodeBlob* cb) { 6603 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6604 if (nm == NULL) { 6605 return; 6606 } 6607 6608 if (ScavengeRootsInCode) { 6609 _g1h->register_nmethod(nm); 6610 } 6611 } 6612 }; 6613 6614 void G1CollectedHeap::rebuild_strong_code_roots() { 6615 RebuildStrongCodeRootClosure blob_cl(this); 6616 CodeCache::blobs_do(&blob_cl); 6617 }